feat(frontend): i18n expansion, admin/profile i18n, grid/list view fix, empty state

- Add 5 new locales (hi, ar, ru, ja, ko) — now 14 total
- Admin panel: 117 i18n keys, confirm modal, animated tabs, no inline handlers
- Profile page: 58 i18n keys with data-i18n attributes
- Fix i18n safeT() shadowing bug and translationsLoaded timing
- Fix grid/list view: list header no longer shows in grid mode on login
- Fix classList.toggle hidden sync for view switching across all nav functions
- Revert .hidden important that broke login page rendering
- Add files empty state (no_files + empty_hint) with translations
- Fix language selector dropdown scroll and styling
- Fix admin panel scroll with sticky tabs

src/interfaces/api/handlers/wopi_handler.rs

@@ -413,14 +413,12 @@ async fn authorize_wopi_access<S: FileRetrievalUseCase>(
 /// This endpoint is behind normal auth middleware. The authenticated user
 /// requests a WOPI session for a specific file.
 pub async fn get_editor_url(
-    AuthUser {
-        id: user_id,
-        username,
-        ..
-    }: AuthUser,
+    auth_user: AuthUser,
     Query(params): Query<EditorUrlParams>,
     State(state): State<WopiState>,
 ) -> Response {
+    let user_id = auth_user.id;
+    let username = &auth_user.username;
     // Verify the caller owns the file (SQL-level check, no existence leak).
     let (file, can_write) = match authorize_wopi_access(
         state.app_state.applications.file_retrieval_service.as_ref(),