feat(frontend): implement center auth session flow with route guard

src/App.tsx

@@ -1,4 +1,5 @@
 import { Navigate, Route, Routes } from 'react-router-dom'
+import ProtectedRoute from './auth/ProtectedRoute'
 import AppLayout from './layouts/AppLayout'
 import ChatPage from './pages/ChatPage'
 import LoginPage from './pages/LoginPage'
@@ -9,8 +10,22 @@ export default function App() {
     <Routes>
       <Route path="/" element={<AppLayout />}>
         <Route index element={<Navigate to="/workspace" replace />} />
-        <Route path="workspace" element={<WorkspacePage />} />
-        <Route path="chat" element={<ChatPage />} />
+        <Route
+          path="workspace"
+          element={
+            <ProtectedRoute>
+              <WorkspacePage />
+            </ProtectedRoute>
+          }
+        />
+        <Route
+          path="chat"
+          element={
+            <ProtectedRoute>
+              <ChatPage />
+            </ProtectedRoute>
+          }
+        />
         <Route path="login" element={<LoginPage />} />
       </Route>
       <Route path="*" element={<Navigate to="/workspace" replace />} />