fix(web): harden typed SPA chat lifecycle

Co-Authored-By: Claude Haiku 4.5 <[email protected]>

apps/web/src/routes.tsx

@@ -4,6 +4,7 @@ import { LoginPage } from '@/spa/pages/login';
 import { RegisterPage } from '@/spa/pages/register';
 import { SsoCallbackPage } from '@/spa/pages/sso-callback';
 import { ChatPage } from '@/spa/pages/chat';
+import { ChatRouteErrorBoundary } from '@/spa/pages/chat-error-boundary';
 import { AuthGuard, GuestGuard } from '@/spa/guards';
 import { Placeholder } from '@/spa/placeholder';
 
@@ -35,7 +36,7 @@ export const routes: RouteObject[] = [
     element: <AuthGuard />,
     children: [
       { path: '/', element: <Navigate to="/chat" replace /> },
-      { path: '/chat', element: <ChatPage /> },
+      { path: '/chat', element: <ChatPage />, errorElement: <ChatRouteErrorBoundary /> },
       { path: '/projects', element: <Placeholder title="Projects" /> },
       { path: '/projects/:id', element: <Placeholder title="Project" /> },
       { path: '/tasks', element: <Placeholder title="Tasks" /> },