feat：简单添加管理员后台功能

client/src/app/AdminLayout.tsx

@@ -0,0 +1,52 @@
+import { Layout, Menu, Typography } from 'antd';
+import { Outlet, useLocation, useNavigate } from 'react-router-dom';
+import { clearAuth } from '../lib/adminAuth';
+
+const { Header, Content, Sider } = Layout;
+
+export function AdminLayout() {
+  const navigate = useNavigate();
+  const location = useLocation();
+
+  const selectedKey = location.pathname.startsWith('/users') ? 'users' : 'users';
+
+  return (
+    <Layout style={{ minHeight: '100vh' }}>
+      <Sider width={220}>
+        <div style={{ padding: 16 }}>
+          <Typography.Title level={5} style={{ color: 'white', margin: 0 }}>
+            Whale Town Admin
+          </Typography.Title>
+        </div>
+        <Menu
+          theme="dark"
+          mode="inline"
+          selectedKeys={[selectedKey]}
+          items={[
+            {
+              key: 'users',
+              label: '用户管理',
+              onClick: () => navigate('/users'),
+            },
+            {
+              key: 'logout',
+              label: '退出登录',
+              onClick: () => {
+                clearAuth();
+                navigate('/login');
+              },
+            },
+          ]}
+        />
+      </Sider>
+      <Layout>
+        <Header style={{ background: 'white', display: 'flex', alignItems: 'center' }}>
+          <Typography.Text>后台管理</Typography.Text>
+        </Header>
+        <Content style={{ padding: 16 }}>
+          <Outlet />
+        </Content>
+      </Layout>
+    </Layout>
+  );
+}

client/src/app/App.tsx

@@ -0,0 +1,26 @@
+import { ConfigProvider } from 'antd';
+import { BrowserRouter, Navigate, Route, Routes } from 'react-router-dom';
+import { AdminLayout } from './AdminLayout';
+import { LoginPage } from '../pages/LoginPage';
+import { UsersPage } from '../pages/UsersPage';
+import { isAuthed } from '../lib/adminAuth';
+
+export function App() {
+  return (
+    <ConfigProvider>
+      <BrowserRouter>
+        <Routes>
+          <Route path="/login" element={<LoginPage />} />
+          <Route
+            path="/"
+            element={isAuthed() ? <AdminLayout /> : <Navigate to="/login" replace />}
+          >
+            <Route index element={<Navigate to="/users" replace />} />
+            <Route path="users" element={<UsersPage />} />
+          </Route>
+          <Route path="*" element={<Navigate to={isAuthed() ? '/users' : '/login'} replace />} />
+        </Routes>
+      </BrowserRouter>
+    </ConfigProvider>
+  );
+}