feat(sidebar): show empty folders and create folders from the sidebar (#999)

Empty folders (tracked in the scan-recorded all_folders list, same source
the move/download destination picker uses) can now be surfaced in the
folder sidebar via a view-options toggle, dimmed when their subtree holds
no models. Folders can be created directly from the sidebar through a new
POST /api/lm/{prefix}/create-folder endpoint with library-root
containment checks; the scanner records the new directory incrementally
so the tree reflects it without a rescan.

The sidebar header moves its view toggles (tree/list, recursive, empty
folders) into a "..." menu to fit the new create-folder button.

locales/de.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "Stammverzeichnis",
         "collapseAll": "Alle Ordner einklappen",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "Seitenleiste auf dieser Seite ausblenden",
         "showSidebar": "Seitenleiste anzeigen",
         "sidebarHiddenNotification": "Seitenleiste auf der Seite {page} ausgeblendet",
-        "switchToListView": "Zur Listenansicht wechseln",
-        "switchToTreeView": "Zur Baumansicht wechseln",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "Unterordner einbeziehen",
-        "recursiveOff": "Nur aktueller Ordner",
-        "recursiveUnavailable": "Rekursive Suche ist nur in der Baumansicht verfügbar",
-        "collapseAllDisabled": "Im Listenmodus nicht verfügbar",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "Zielpfad für das Verschieben konnte nicht ermittelt werden.",
             "moveUnsupported": "Verschieben wird für dieses Element nicht unterstützt.",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "Keine Ordner gefunden",
-            "dragHint": "Elemente hierher ziehen, um Ordner zu erstellen"
+            "dragHint": "Elemente hierher ziehen, um Ordner zu erstellen",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "Auf Updates in diesem Ordner prüfen",

locales/en.json

@@ -1246,15 +1246,23 @@
   "sidebar": {
     "modelRoot": "Root",
     "collapseAll": "Collapse All Folders",
+    "collapseAllDisabled": "Not available in list view",
     "hideOnThisPage": "Hide sidebar on this page",
     "showSidebar": "Show sidebar",
     "sidebarHiddenNotification": "Folder sidebar hidden on {page} page",
-    "switchToListView": "Switch to List View",
-    "switchToTreeView": "Switch to Tree View",
+    "viewOptions": "View options",
+    "treeView": "Tree view",
+    "listView": "List view",
     "recursiveOn": "Include subfolders",
-    "recursiveOff": "Current folder only",
-    "recursiveUnavailable": "Recursive search is available in tree view only",
-    "collapseAllDisabled": "Not available in list view",
+    "createFolder": "New folder",
+    "newSubfolder": "New subfolder",
+    "showEmptyFolders": "Show empty folders",
+    "createFolderResult": {
+      "success": "Folder \"{name}\" created",
+      "failed": "Failed to create folder: {message}",
+      "unsupported": "Folder creation is not supported on this page",
+      "noRoot": "No model root is configured"
+    },
     "dragDrop": {
       "unableToResolveRoot": "Unable to determine destination path for move.",
       "moveUnsupported": "Move is not supported for this item.",
@@ -1267,7 +1275,8 @@
     },
     "empty": {
       "noFolders": "No folders found",
-      "dragHint": "Drag items here to create folders"
+      "dragHint": "Drag items here to create folders",
+      "createHint": "Click the New Folder button above, or drag items here to create folders"
     },
     "folderUpdateCheck": {
       "label": "Check for updates in this folder",

locales/es.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "Raíz",
         "collapseAll": "Colapsar todas las carpetas",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "Ocultar barra lateral en esta página",
         "showSidebar": "Mostrar barra lateral",
         "sidebarHiddenNotification": "Barra lateral oculta en la página {page}",
-        "switchToListView": "Cambiar a vista de lista",
-        "switchToTreeView": "Cambiar a vista de árbol",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "Incluir subcarpetas",
-        "recursiveOff": "Solo carpeta actual",
-        "recursiveUnavailable": "La búsqueda recursiva solo está disponible en la vista en árbol",
-        "collapseAllDisabled": "No disponible en vista de lista",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "No se puede determinar la ruta de destino para el movimiento.",
             "moveUnsupported": "El movimiento no es compatible con este elemento.",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "No se encontraron carpetas",
-            "dragHint": "Arrastra elementos aquí para crear carpetas"
+            "dragHint": "Arrastra elementos aquí para crear carpetas",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "Buscar actualizaciones en esta carpeta",

locales/fr.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "Racine",
         "collapseAll": "Réduire tous les dossiers",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "Masquer la barre latérale sur cette page",
         "showSidebar": "Afficher la barre latérale",
         "sidebarHiddenNotification": "Barre latérale masquée sur la page {page}",
-        "switchToListView": "Passer en vue liste",
-        "switchToTreeView": "Passer en vue arborescence",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "Inclure les sous-dossiers",
-        "recursiveOff": "Dossier actuel uniquement",
-        "recursiveUnavailable": "La recherche récursive n'est disponible qu'en vue arborescente",
-        "collapseAllDisabled": "Non disponible en vue liste",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "Impossible de déterminer le chemin de destination pour le déplacement.",
             "moveUnsupported": "Le déplacement n'est pas pris en charge pour cet élément.",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "Aucun dossier trouvé",
-            "dragHint": "Faites glisser des éléments ici pour créer des dossiers"
+            "dragHint": "Faites glisser des éléments ici pour créer des dossiers",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "Vérifier les mises à jour dans ce dossier",

locales/he.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "שורש",
         "collapseAll": "כווץ את כל התיקיות",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "הסתר סרגל צד בדף זה",
         "showSidebar": "הצג סרגל צד",
         "sidebarHiddenNotification": "סרגל הצד מוסתר בדף {page}",
-        "switchToListView": "עבור לתצוגת רשימה",
-        "switchToTreeView": "תצוגת עץ",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "כלול תיקיות משנה",
-        "recursiveOff": "רק התיקייה הנוכחית",
-        "recursiveUnavailable": "חיפוש רקורסיבי זמין רק בתצוגת עץ",
-        "collapseAllDisabled": "לא זמין בתצוגת רשימה",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "לא ניתן לקבוע את נתיב היעד להעברה.",
             "moveUnsupported": "העברה אינה נתמכת עבור פריט זה.",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "לא נמצאו תיקיות",
-            "dragHint": "גרור פריטים לכאן כדי ליצור תיקיות"
+            "dragHint": "גרור פריטים לכאן כדי ליצור תיקיות",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "בדוק עדכונים בתיקייה זו",

locales/ja.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "ルート",
         "collapseAll": "すべてのフォルダを折りたたむ",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "このページでサイドバーを非表示",
         "showSidebar": "サイドバーを表示",
         "sidebarHiddenNotification": "{page}ページでサイドバーが非表示になっています",
-        "switchToListView": "リストビューに切り替え",
-        "switchToTreeView": "ツリー表示に切り替え",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "サブフォルダーを含める",
-        "recursiveOff": "現在のフォルダーのみ",
-        "recursiveUnavailable": "再帰検索はツリービューでのみ利用できます",
-        "collapseAllDisabled": "リストビューでは利用できません",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "移動先のパスを特定できません。",
             "moveUnsupported": "この項目の移動はサポートされていません。",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "フォルダが見つかりません",
-            "dragHint": "ここへアイテムをドラッグしてフォルダを作成します"
+            "dragHint": "ここへアイテムをドラッグしてフォルダを作成します",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "このフォルダのアップデートを確認",

locales/ko.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "루트",
         "collapseAll": "모든 폴더 접기",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "이 페이지에서 사이드바 숨기기",
         "showSidebar": "사이드바 표시",
         "sidebarHiddenNotification": "{page} 페이지에서 사이드바가 숨겨져 있습니다",
-        "switchToListView": "목록 보기로 전환",
-        "switchToTreeView": "트리 보기로 전환",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "하위 폴더 포함",
-        "recursiveOff": "현재 폴더만",
-        "recursiveUnavailable": "재귀 검색은 트리 보기에서만 사용할 수 있습니다",
-        "collapseAllDisabled": "목록 보기에서는 사용할 수 없습니다",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "이동할 대상 경로를 확인할 수 없습니다.",
             "moveUnsupported": "이 항목은 이동을 지원하지 않습니다.",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "폴더를 찾을 수 없습니다",
-            "dragHint": "항목을 여기로 드래그하여 폴더를 만듭니다"
+            "dragHint": "항목을 여기로 드래그하여 폴더를 만듭니다",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "이 폴더의 업데이트 확인",

locales/ru.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "Корень",
         "collapseAll": "Свернуть все папки",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "Скрыть боковую панель на этой странице",
         "showSidebar": "Показать боковую панель",
         "sidebarHiddenNotification": "Боковая панель скрыта на странице {page}",
-        "switchToListView": "Переключить на вид списка",
-        "switchToTreeView": "Переключить на древовидный вид",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "Включать вложенные папки",
-        "recursiveOff": "Только текущая папка",
-        "recursiveUnavailable": "Рекурсивный поиск доступен только в режиме дерева",
-        "collapseAllDisabled": "Недоступно в виде списка",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "Не удалось определить путь назначения для перемещения.",
             "moveUnsupported": "Перемещение этого элемента не поддерживается.",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "Папки не найдены",
-            "dragHint": "Перетащите элементы сюда, чтобы создать папки"
+            "dragHint": "Перетащите элементы сюда, чтобы создать папки",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "Проверить обновления в этой папке",

locales/zh-CN.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "根目录",
         "collapseAll": "折叠所有文件夹",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "隐藏此页面侧边栏",
         "showSidebar": "显示侧边栏",
         "sidebarHiddenNotification": "{page}页面的文件夹侧边栏已隐藏",
-        "switchToListView": "切换到列表视图",
-        "switchToTreeView": "切换到树状视图",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "包含子文件夹",
-        "recursiveOff": "仅当前文件夹",
-        "recursiveUnavailable": "仅在树形视图中可使用递归搜索",
-        "collapseAllDisabled": "列表视图下不可用",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "无法确定移动的目标路径。",
             "moveUnsupported": "此条目不支持移动。",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "未找到文件夹",
-            "dragHint": "拖拽项目到此处以创建文件夹"
+            "dragHint": "拖拽项目到此处以创建文件夹",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "检查此文件夹的更新",

locales/zh-TW.json

@@ -1246,15 +1246,23 @@
     "sidebar": {
         "modelRoot": "根目錄",
         "collapseAll": "全部摺疊資料夾",
+        "collapseAllDisabled": "[TODO: Translate] Not available in list view",
         "hideOnThisPage": "隱藏此頁面側邊欄",
         "showSidebar": "顯示側邊欄",
         "sidebarHiddenNotification": "{page}頁面的資料夾側邊欄已隱藏",
-        "switchToListView": "切換至列表檢視",
-        "switchToTreeView": "切換到樹狀檢視",
+        "viewOptions": "[TODO: Translate] View options",
+        "treeView": "[TODO: Translate] Tree view",
+        "listView": "[TODO: Translate] List view",
         "recursiveOn": "包含子資料夾",
-        "recursiveOff": "僅目前資料夾",
-        "recursiveUnavailable": "遞迴搜尋僅能在樹狀檢視中使用",
-        "collapseAllDisabled": "列表檢視下不可用",
+        "createFolder": "[TODO: Translate] New folder",
+        "newSubfolder": "[TODO: Translate] New subfolder",
+        "showEmptyFolders": "[TODO: Translate] Show empty folders",
+        "createFolderResult": {
+            "success": "[TODO: Translate] Folder \"{name}\" created",
+            "failed": "[TODO: Translate] Failed to create folder: {message}",
+            "unsupported": "[TODO: Translate] Folder creation is not supported on this page",
+            "noRoot": "[TODO: Translate] No model root is configured"
+        },
         "dragDrop": {
             "unableToResolveRoot": "無法確定移動的目標路徑。",
             "moveUnsupported": "此項目不支援移動。",
@@ -1267,7 +1275,8 @@
         },
         "empty": {
             "noFolders": "未找到資料夾",
-            "dragHint": "將項目拖到此處以建立資料夾"
+            "dragHint": "將項目拖到此處以建立資料夾",
+            "createHint": "[TODO: Translate] Click the New Folder button above, or drag items here to create folders"
         },
         "folderUpdateCheck": {
             "label": "檢查此資料夾的更新",