fix(desktop): register ChatPage element in router

The /chat route was missing its element prop, causing React Router
to render an empty Outlet.

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

apps/desktop/src/App.tsx

@@ -1,6 +1,7 @@
 import { createHashRouter, RouterProvider } from 'react-router-dom'
 import Layout from './pages/layout'
 import HomePage from './pages/home'
+import ChatPage from './pages/chat'
 import ToolsPage from './pages/tools'
 import SkillsPage from './pages/skills'
 
@@ -10,7 +11,7 @@ const router = createHashRouter([
     element: <Layout />,
     children: [
       { index: true, element: <HomePage /> },
-      { path: 'chat' },
+      { path: 'chat', element: <ChatPage /> },
       { path: 'tools', element: <ToolsPage /> },
       { path: 'skills', element: <SkillsPage /> },
     ],