refactor(settings): restructure settings modal with subsection headers

- Replace duplicate section headers with meaningful subsection titles
- Group settings under logical subsections using existing i18n keys
- Add new translation key 'settings.sections.apiConfiguration'
- Update CSS for subsection styling with proper visual hierarchy
- Improve UX by making settings organization clearer

Subsections now use familiar titles from existing translations:
- API Configuration, Storage Location, Language (General)
- Content Filtering, Video Settings, Layout Settings (Interface)
- Folder Settings, Download Path Templates, Priority Tags,
  Update Flags, Example Images (Download)
- Auto-organize Exclusions, Metadata Refresh Skip Paths (Organization)
- Metadata Archive, Misc (System)
- Proxy Settings (Network)

locales/de.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "Einstellungspfad: {{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "Inhaltsfilterung",
             "videoSettings": "Video-Einstellungen",
             "layoutSettings": "Layout-Einstellungen",

locales/en.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "Settings path: {{path}}"
         },
         "sections": {
+            "apiConfiguration": "API Configuration",
             "contentFiltering": "Content Filtering",
             "videoSettings": "Video Settings",
             "layoutSettings": "Layout Settings",

locales/es.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "Ruta de configuración: {{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "Filtrado de contenido",
             "videoSettings": "Configuración de video",
             "layoutSettings": "Configuración de diseño",

locales/fr.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "Chemin des paramètres: {{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "Filtrage du contenu",
             "videoSettings": "Paramètres vidéo",
             "layoutSettings": "Paramètres d'affichage",

locales/he.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "נתיב ההגדרות: {{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "סינון תוכן",
             "videoSettings": "הגדרות וידאו",
             "layoutSettings": "הגדרות פריסה",

locales/ja.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "設定パス: {{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "コンテンツフィルタリング",
             "videoSettings": "動画設定",
             "layoutSettings": "レイアウト設定",

locales/ko.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "설정 경로: {{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "콘텐츠 필터링",
             "videoSettings": "비디오 설정",
             "layoutSettings": "레이아웃 설정",

locales/ru.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "Путь настроек: {{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "Фильтрация контента",
             "videoSettings": "Настройки видео",
             "layoutSettings": "Настройки макета",

locales/zh-CN.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "设置路径：{{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "内容过滤",
             "videoSettings": "视频设置",
             "layoutSettings": "布局设置",

locales/zh-TW.json

@@ -255,6 +255,7 @@
             "clipboardFallback": "設定路徑：{{path}}"
         },
         "sections": {
+            "apiConfiguration": "[TODO: Translate] API Configuration",
             "contentFiltering": "內容過濾",
             "videoSettings": "影片設定",
             "layoutSettings": "版面設定",