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

static/js/app/main.js

@@ -473,8 +473,8 @@ function setupEventListeners() {
                 // Show files containers (to be filled with trash)
                 const filesGrid = document.getElementById('files-grid');
                 const filesListView = document.getElementById('files-list-view');
-                if (filesGrid) filesGrid.style.display = app.currentView === 'grid' ? 'grid' : 'none';
-                if (filesListView) filesListView.style.display = app.currentView === 'list' ? 'block' : 'none';
+                if (filesGrid) { filesGrid.style.display = app.currentView === 'grid' ? 'grid' : 'none'; filesGrid.classList.toggle('hidden', app.currentView !== 'grid'); }
+                if (filesListView) { filesListView.style.display = app.currentView === 'list' ? 'flex' : 'none'; filesListView.classList.toggle('hidden', app.currentView !== 'list'); }
                 
                 // Update UI
                 elements.pageTitle.textContent = window.i18n ? window.i18n.t('nav.trash') : 'Trash';
@@ -494,6 +494,8 @@ function setupEventListeners() {
     const savedView = localStorage.getItem('oxicloud-view');
     if (savedView === 'list') {
         ui.switchToListView();
+    } else {
+        ui.switchToGridView();
     }
     
     // User menu