feat: add notifications and project shares features

- Backend: notifications + shares routes, DB tables, SqliteAdapter methods
- Frontend: NotificationPanel (bell icon + dropdown), ShareDialog, Dashboard integration
- Styles: notification + share dialog CSS

backend/src/server.ts

@@ -57,6 +57,8 @@ export async function createServer(opts: ServerOptions) {
   const { registerAuthRoutes } = await import('./routes/auth.js');
   const { registerUserRoutes } = await import('./routes/users.js');
   const { registerAIRoutes } = await import('./routes/ai.js');
+  const { registerNotificationRoutes } = await import('./routes/notifications.js');
+  const { registerShareRoutes } = await import('./routes/shares.js');
 
   const authService = new AuthService(opts.db);
 
@@ -69,6 +71,8 @@ export async function createServer(opts: ServerOptions) {
   registerSettingsRoutes(fastify, opts.db);
   registerUserRoutes(fastify, opts.db, authService);
   registerAIRoutes(fastify, authService);
+  registerNotificationRoutes(fastify, opts.db, authService);
+  registerShareRoutes(fastify, opts.db, authService);
 
   // Yjs collaboration WebSocket
   registerYjsWebSocket(fastify);