feat(05-02): add widget settings panel with search provider form

- Settings > Dashboard page with per-widget-instance config
- Clock config: timezone select (IANA list) + date toggle (D-12/D-13)
- Note config: editable title field (D-17)
- Search config: SearchProviderForm with add/delete and {query} validation (D-15)
- Calendar config: link to calendar-specific settings
- i18n keys for search provider management (en + de)
- Fix useRef initialization for React 19 strict mode (note-widget)
- Fix unknown type narrowing in widget title display

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

apps/web/src/components/dashboard/widgets/note-widget.tsx

@@ -41,8 +41,8 @@ export function NoteWidget({ instanceId, config }: WidgetProps) {
   );
   const [saveError, setSaveError] = useState(false);
 
-  const timerRef = useRef<ReturnType<typeof setTimeout>>();
-  const abortRef = useRef<AbortController>();
+  const timerRef = useRef<ReturnType<typeof setTimeout> | undefined>(undefined);
+  const abortRef = useRef<AbortController | undefined>(undefined);
 
   // Cleanup on unmount
   useEffect(() => {