feat: 添加聊天功能及相关路由配置和UI组件，并引入 react-icons 依赖。

src/router/index.tsx

@@ -17,6 +17,7 @@ import Profile from '../pages/Profile';
 import GitHubCallback from '../pages/GitHubCallback';
 import GiteeCallback from '../pages/GiteeCallback';
 import Notifications from '../pages/Notifications';
+import Chat from '../pages/Chat';
 import Layout from '../components/common/Layout';
 import ProtectedRoute from '../components/common/ProtectedRoute';
 
@@ -53,6 +54,10 @@ export const router = createBrowserRouter([
         path: 'home',
         element: <Home />,
       },
+      {
+        path: 'chat',
+        element: <Chat />,
+      },
       {
         path: 'transactions',
         element: <Transactions />,