feat(ui): SVG图标全替换 + Neo-Brutalist主题升级 + 数据导出卡片类别勾选

client/src/pages/admin/Login.tsx

@@ -3,6 +3,7 @@ import { useNavigate } from 'react-router-dom';
 import Input from '../../components/Input';
 import Button from '../../components/Button';
 import { authApi, errMsg } from '../../api';
+import { IconLogo } from '../../components/Icons';
 
 export default function Login() {
   const [username, setUsername] = useState('admin');
@@ -34,8 +35,8 @@ export default function Login() {
   return (
     <div className="min-h-screen flex items-center justify-center bg-gray-50 px-4">
       <form onSubmit={submit} className="w-full max-w-md bg-white border-2 border-black p-6 md:p-8">
-        <div className="text-center mb-6">
-          <div className="text-4xl mb-2">🕒</div>
+        <div className="text-center mb-6 flex flex-col items-center">
+          <div className="mb-2 text-black"><IconLogo size={48} /></div>
           <h1 className="text-2xl font-black tracking-wide">义工时长管理系统</h1>
           <p className="text-gray-500 text-sm mt-1">管理台登录</p>
         </div>