feat: add auth, real-time collaboration, sharing, font control, and UI fixes

Phase 1 - Bug fixes:
- Fix color labels not showing on active line in format preview
- Replace eye emoji with SVG icon showing clear preview/raw state
- Replace // button with comment icon + better tooltip
- Fix ThemePicker accent colors when using system theme

Phase 2 - Font:
- Load JetBrains Mono via Google Fonts with offline fallback
- Add font size control (A-/A+) with keyboard shortcuts
- Persist font size preference in localStorage

Phase 3 - Auth:
- Supabase-based email/password authentication
- Device session management with configurable password renewal TTL
- AuthModal, UserMenu, SecuritySettings components

Phase 4 - Cloud sync:
- Document metadata sync to Supabase PostgreSQL
- Legacy localStorage migration on first login
- IndexedDB persistence via y-indexeddb

Phase 5 - Real-time collaboration:
- Y.js CRDT integration with CodeMirror 6
- Hocuspocus WebSocket server with JWT auth
- Collaborative cursor awareness
- CollabIndicator component

Phase 6 - Sharing:
- Share links with view/edit permissions
- ShareDialog component with copy-to-clipboard
- Minimal client-side router for /s/{token} URLs

Infrastructure:
- Docker Compose with PostgreSQL, GoTrue, PostgREST, Hocuspocus
- Nginx reverse proxy for all backend services
- SQL migrations with RLS policies
- Production-ready Dockerfile with build args

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

collab-server/tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "outDir": "dist",
+    "rootDir": "src",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true
+  },
+  "include": ["src"]
+}