feat(05-02): add search and note widgets with tests

- SearchWidget: provider dropdown, text input, button; opens search in new tab via window.open (D-14/D-15)
- NoteWidget: MDEditor with compact toolbar, debounced autosave (1500ms), AbortController for in-flight cancellation (D-16/D-17/D-18)
- rehype-sanitize enabled for Markdown XSS prevention (T-05-05)
- Widget registry updated with wireSearchWidget/wireNoteWidget (no more placeholders)
- dashboard-api.ts: added fetchSearchProviders, addSearchProvider, removeSearchProvider, signal support on updateWidgetConfig
- 9 new tests passing (search: 5, note: 4)

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

apps/web/src/app/(portal)/page.tsx

@@ -5,13 +5,17 @@ import { useTranslations } from 'next-intl';
 import { DashboardGrid } from '@/components/dashboard/dashboard-grid';
 import { EditModeToggle } from '@/components/dashboard/edit-mode-toggle';
 import { WidgetCatalogModal } from '@/components/dashboard/widget-catalog-modal';
-import { wireClockWidget } from '@/components/dashboard/widget-registry';
+import { wireClockWidget, wireSearchWidget, wireNoteWidget } from '@/components/dashboard/widget-registry';
 import { ClockWidget } from '@/components/dashboard/widgets/clock-widget';
+import { SearchWidget } from '@/components/dashboard/widgets/search-widget';
+import { NoteWidget } from '@/components/dashboard/widgets/note-widget';
 import { useDashboardStore } from '@/lib/stores/dashboard-store';
 import type { WidgetType } from '@/components/dashboard/widget-registry';
 
-// Wire ClockWidget into the registry (deferred to avoid circular deps)
+// Wire widget components into the registry (deferred to avoid circular deps)
 wireClockWidget(ClockWidget);
+wireSearchWidget(SearchWidget);
+wireNoteWidget(NoteWidget);
 
 export default function DashboardPage() {
   const t = useTranslations('widgets');