refactor(reorder): drop the Alt + Arrow shortcut, keep drag only

The reorder shortcut cannot be made reliable in this UI. `Alt + Arrow` is
the browser's tab-history / back-forward gesture on several platforms,
and the modal already binds bare `ArrowLeft`/`ArrowRight` to model
navigation, so the binding either did nothing — a keypress with nothing
focused never reaches a listener on the tag list — or fought the browser.
An affordance that occasionally navigates the page away is worse than
having no keyboard path at all, so drop it.

Reordering is pointer-only again: drag the chip (tags) or its `⠿` grip
(trigger words, whose chip body is click-to-edit). Everything that existed
only to serve the shortcut goes with it — the keydown listener, the hover
tracking used to resolve the target chip, the aria-live announcements, the
per-grip position labels and `moveItemWithinContainer`. The grip becomes a
decorative, non-focusable `<span>` (`aria-hidden`, behind a 5px drag
threshold) instead of a `<button>`, so it no longer promises a keyboard
action it cannot perform.

The tooltip and hint drop the shortcut mention in all 10 locales
(`common.reorder.dragHandle` = "Drag to reorder" and the localised
equivalents); `common.reorder.ariaLabel` and `common.reorder.announcement`
are pruned from every locale by the sync script. The i18n guidelines
record the decision so no shortcut is re-added without re-adding the keys.

locales/de.json

@@ -3,9 +3,7 @@
         "cancel": "Abbrechen",
         "confirm": "Bestätigen",
         "reorder": {
-            "dragHandle": "Zum Neuordnen ziehen (Alt + ↑/↓)",
-            "ariaLabel": "{item} neu anordnen, Position {position} von {total}",
-            "announcement": "An Position {position} von {total} verschoben"
+            "dragHandle": "Zum Neuordnen ziehen"
         },
         "actions": {
             "save": "Speichern",

locales/en.json

@@ -3,9 +3,7 @@
     "cancel": "Cancel",
     "confirm": "Confirm",
     "reorder": {
-      "dragHandle": "Drag to reorder (Alt + ↑/↓)",
-      "ariaLabel": "Reorder {item}, position {position} of {total}",
-      "announcement": "Moved to position {position} of {total}"
+      "dragHandle": "Drag to reorder"
     },
     "actions": {
       "save": "Save",

locales/es.json

@@ -3,9 +3,7 @@
         "cancel": "Cancelar",
         "confirm": "Confirmar",
         "reorder": {
-            "dragHandle": "Arrastra para reordenar (Alt + ↑/↓)",
-            "ariaLabel": "Reordenar {item}, posición {position} de {total}",
-            "announcement": "Movido a la posición {position} de {total}"
+            "dragHandle": "Arrastra para reordenar"
         },
         "actions": {
             "save": "Guardar",

locales/fr.json

@@ -3,9 +3,7 @@
         "cancel": "Annuler",
         "confirm": "Confirmer",
         "reorder": {
-            "dragHandle": "Glisser pour réordonner (Alt + ↑/↓)",
-            "ariaLabel": "Réordonner {item}, position {position} sur {total}",
-            "announcement": "Déplacé en position {position} sur {total}"
+            "dragHandle": "Glisser pour réordonner"
         },
         "actions": {
             "save": "Enregistrer",

locales/he.json

@@ -3,9 +3,7 @@
         "cancel": "ביטול",
         "confirm": "אישור",
         "reorder": {
-            "dragHandle": "גרור כדי לשנות סדר (Alt + ↑/↓)",
-            "ariaLabel": "סדר מחדש את {item}, מיקום {position} מתוך {total}",
-            "announcement": "הועבר למיקום {position} מתוך {total}"
+            "dragHandle": "גרור כדי לשנות סדר"
         },
         "actions": {
             "save": "שמירה",

locales/ja.json

@@ -3,9 +3,7 @@
         "cancel": "キャンセル",
         "confirm": "確認",
         "reorder": {
-            "dragHandle": "ドラッグして並べ替え（Alt + ↑/↓）",
-            "ariaLabel": "{item} を並べ替え、{total} 件中 {position} 番目",
-            "announcement": "{total} 件中 {position} 番目に移動しました"
+            "dragHandle": "ドラッグして並べ替え"
         },
         "actions": {
             "save": "保存",

locales/ko.json

@@ -3,9 +3,7 @@
         "cancel": "취소",
         "confirm": "확인",
         "reorder": {
-            "dragHandle": "드래그하여 순서 변경 (Alt + ↑/↓)",
-            "ariaLabel": "{item} 순서 변경, 총 {total}개 중 {position}번째",
-            "announcement": "총 {total}개 중 {position}번째로 이동했습니다"
+            "dragHandle": "드래그하여 순서 변경"
         },
         "actions": {
             "save": "저장",

locales/ru.json

@@ -3,9 +3,7 @@
         "cancel": "Отмена",
         "confirm": "Подтвердить",
         "reorder": {
-            "dragHandle": "Перетащите, чтобы изменить порядок (Alt + ↑/↓)",
-            "ariaLabel": "Изменить порядок {item}, позиция {position} из {total}",
-            "announcement": "Перемещено на позицию {position} из {total}"
+            "dragHandle": "Перетащите, чтобы изменить порядок"
         },
         "actions": {
             "save": "Сохранить",

locales/zh-CN.json

@@ -3,9 +3,7 @@
         "cancel": "取消",
         "confirm": "确认",
         "reorder": {
-            "dragHandle": "拖拽以调整顺序（Alt + ↑/↓）",
-            "ariaLabel": "调整 {item} 的顺序，第 {position} 个，共 {total} 个",
-            "announcement": "已移动到第 {position} 个，共 {total} 个"
+            "dragHandle": "拖拽以调整顺序"
         },
         "actions": {
             "save": "保存",

locales/zh-TW.json

@@ -3,9 +3,7 @@
         "cancel": "取消",
         "confirm": "確認",
         "reorder": {
-            "dragHandle": "拖曳以調整順序（Alt + ↑/↓）",
-            "ariaLabel": "調整 {item} 的順序，第 {position} 個，共 {total} 個",
-            "announcement": "已移動到第 {position} 個，共 {total} 個"
+            "dragHandle": "拖曳以調整順序"
         },
         "actions": {
             "save": "儲存",