feat: Phase 5 - Calendar + Dashboard + Search

Calendar:
- GET /api/domains/[domainId]/calendar/events?from=&to= — returns tasks, habits, projects, milestones
- PATCH /api/domains/[domainId]/tasks/[id]/schedule — drag-to-reschedule with activity feed
- Calendar UI with month/week/day views via react-big-calendar
- Drag-to-reschedule with SSE updates
- Filter by entity type and domain
- Keyboard shortcuts: t=today, m/w/d=view, ←/→=navigate
- Mobile: auto-switches to day view on small screens

Dashboard:
- GET/PUT /api/domains/[domainId]/dashboard — layout stored in domain custom_fields
- 8 per-widget data endpoints (today-tasks, habit-checklist, weekly-stats, project-progress, upcoming-calendar, recent-notes, activity-feed, quick-capture)
- react-grid-layout with responsive breakpoints (12/8/4 cols)
- Drag-to-reorder, resize, add/remove widgets
- Edit mode toggle, per-workspace layout persistence
- Widget error boundary

Search:
- tsvector columns + GIN indexes on tasks, notes, projects, habits, domains
- GET /api/search?q=&types=&domain= — ranked results with ts_headline snippets
- Dedicated search page with grouped results, filters, recent searches (localStorage)
- Empty state with hints

Schema:
- Added custom_fields jsonb column to domains table (migration 0002)
- Removed stale root app/ directory

Build: passes, typecheck: passes, tests: 18/18 wikilink-parser tests pass

apps/web/components/sidebar.tsx

@@ -12,6 +12,7 @@ import {
   NotebookPen,
   Share2,
   CalendarDays,
+  Search,
   Bot,
   Settings,
   ChevronLeft,
@@ -42,6 +43,7 @@ const navItems = [
   { href: '/notes', label: 'Notes', icon: NotebookPen },
   { href: '/graph', label: 'Graph', icon: Share2 },
   { href: '/calendar', label: 'Calendar', icon: CalendarDays },
+  { href: '/search', label: 'Search', icon: Search },
 ];
 
 const workspaceItems = [