feat：简单添加管理员后台功能

client/src/pages/LoginPage.tsx

@@ -0,0 +1,50 @@
+import { Button, Card, Form, Input, Typography, message } from 'antd';
+import { useNavigate } from 'react-router-dom';
+import { api } from '../lib/api';
+import { setToken } from '../lib/adminAuth';
+
+type LoginValues = {
+  identifier: string;
+  password: string;
+};
+
+export function LoginPage() {
+  const navigate = useNavigate();
+  const [form] = Form.useForm<LoginValues>();
+
+  const onFinish = async (values: LoginValues) => {
+    try {
+      const res = await api.adminLogin(values.identifier, values.password);
+      if (!res?.success || !res?.data?.access_token) {
+        throw new Error(res?.message || '登录失败');
+      }
+
+      setToken(res.data.access_token);
+      message.success('登录成功');
+      navigate('/users');
+    } catch (e: any) {
+      message.error(e?.message || '登录失败');
+    }
+  };
+
+  return (
+    <div style={{ minHeight: '100vh', display: 'flex', justifyContent: 'center', alignItems: 'center' }}>
+      <Card style={{ width: 420 }}>
+        <Typography.Title level={4} style={{ marginTop: 0 }}>
+          管理员登录
+        </Typography.Title>
+        <Form form={form} layout="vertical" onFinish={onFinish}>
+          <Form.Item name="identifier" label="用户名/邮箱/手机号" rules={[{ required: true }]}>
+            <Input placeholder="admin" autoComplete="username" />
+          </Form.Item>
+          <Form.Item name="password" label="密码" rules={[{ required: true }]}>
+            <Input.Password placeholder="请输入密码" autoComplete="current-password" />
+          </Form.Item>
+          <Button type="primary" htmlType="submit" block>
+            登录
+          </Button>
+        </Form>
+      </Card>
+    </div>
+  );
+}