feat: dark mode complet + préférences utilisateur

- Ajout du store userPreferencesStore (thème, vue, tri, pagination, lecteur)
- Page UserPreferencesPage pour configurer toutes les préférences
- Câblage des prefs dans HomePage (viewMode, sortBy, itemsPerPage), readerStore (fallback prefs), ChapterReader (autoHide, autoFullscreen, sync), useNotifications (toastDuration)
- Thème sombre (dark: Tailwind) sur tous les composants Vue : Layout, Pagination, NotificationToast, MangaCard, MangaVolume, MangaDetails, AddManga, HomePage, ActivityPage, JobItem, MangaDeleteModal, MangaEditModal, MangaPreferredSourcesModal, ManageChaptersModal, MangaChapterList, MangaChapter, ConversionPage, FileUploadArea, ConversionProgress, NewImportPage, FileImportCard, MangaMatchCard, StatusBadge, ImportResults
- i18n partiellement initialisé

Jeremy Guillot

assets/vue/app/shared/i18n/locales/en.json

@@ -0,0 +1,67 @@
+{
+  "nav": {
+    "preferences": "Preferences"
+  },
+  "preferences": {
+    "title": "Preferences",
+    "subtitle": "Customize the interface to your liking",
+    "reset": "Reset",
+    "resetConfirm": "Reset to default values?",
+    "sections": {
+      "appearance": "Appearance",
+      "collection": "Collection display",
+      "reading": "Reading",
+      "notifications": "Notifications"
+    },
+    "theme": {
+      "label": "Theme",
+      "light": "Light",
+      "dark": "Dark",
+      "system": "System (automatic)"
+    },
+    "language": {
+      "label": "Language",
+      "fr": "Français",
+      "en": "English"
+    },
+    "defaultView": {
+      "label": "Default view",
+      "grid": "Grid",
+      "list": "List"
+    },
+    "itemsPerPage": {
+      "label": "Mangas per page"
+    },
+    "sortBy": {
+      "label": "Default sort",
+      "title": "Title",
+      "addedAt": "Date added",
+      "progress": "Progress"
+    },
+    "readingDirection": {
+      "label": "Reading direction",
+      "ltr": "Left → Right (western)",
+      "rtl": "Right → Left (manga)"
+    },
+    "readingMode": {
+      "label": "Display mode",
+      "scroll": "Vertical scroll",
+      "single": "Single page",
+      "double": "Double page"
+    },
+    "autoFullscreen": {
+      "label": "Auto fullscreen",
+      "description": "Enter fullscreen when starting the reader"
+    },
+    "autoHideHeaderReader": {
+      "label": "Auto-hide header",
+      "description": "Hide the navigation bar in reading mode"
+    },
+    "toastDuration": {
+      "label": "Notification duration",
+      "3s": "3 seconds",
+      "5s": "5 seconds",
+      "10s": "10 seconds"
+    }
+  }
+}