fix: schema init, duplicate routes, and image preview bugs

- Move pg_trgm extension creation before CalDAV indexes that depend on it
- Remove duplicate app-password route registration that caused panic
- Fix missing comma in language selector array (Dutch entry)
- Await async canEdit() in file click handler (Promise was always truthy)
- Detect images by extension fallback when mime_type is octet-stream
  (files uploaded via Nextcloud WebDAV API lack correct mime types)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

static/js/core/languageSelector.js

@@ -17,7 +17,7 @@ function getAvailableLanguages() {
         { code: 'fr', name: 'Français', flag: '🇫🇷' },
         { code: 'de', name: 'Deutsch', flag: '🇩🇪' },
         { code: 'pt', name: 'Português', flag: '🇧🇷' },
-        { code: 'it', name: 'Italiano', flag: '🇮🇹' }
+        { code: 'it', name: 'Italiano', flag: '🇮🇹' },
         { code: 'nl', name: 'Nederlands', flag: '🇳🇱' }
     ];
 }