refactor: 前端 UI 框架从 TDesign 迁移到 antd 6.x

- 移除 tdesign-react + tdesign-icons-react，新增 antd@6.4.3 + @ant-design/icons@6.2.3
- Layout/Header/Sider/Content 替换 TDesign Layout，Sider 内置折叠管理
- Segmented 替换 RadioGroup 主题切换，ConfigProvider 主题算法切换
- Menu items prop 模式，Sidebar 简化为无 props 纯组件
- Table/Modal/Form/Input.TextArea/Tabs/Tag/Popconfirm 全量迁移
- App.useApp().message 替换 MessagePlugin（hooks 模式）
- --td-* CSS 变量替换为 --ant-* antd CSS 变量
- 测试适配：ConfigProvider+App wrapper，.ant-menu-item-selected，antd CSS-in-JS jsdom 兼容
- 文档更新：frontend.md, development/README.md, config.yaml, deploy.md
- vendor-antd chunk 755KB gzipped 240KB

src/web/pages/404/index.tsx

@@ -1,6 +1,6 @@
+import { ExclamationCircleOutlined } from "@ant-design/icons";
+import { Button, Space } from "antd";
 import { useNavigate } from "react-router";
-import { ErrorCircleIcon } from "tdesign-icons-react";
-import { Button, Space } from "tdesign-react";
 
 export function NotFoundPage() {
   const navigate = useNavigate();
@@ -10,11 +10,11 @@ export function NotFoundPage() {
   };
 
   return (
-    <Space align="center" className="not-found-page" direction="vertical" size="large">
-      <ErrorCircleIcon className="not-found-icon" size="64px" />
+    <Space align="center" className="not-found-page" size="large" vertical>
+      <ExclamationCircleOutlined className="not-found-icon" />
       <h1>404</h1>
       <p>您访问的页面不存在</p>
-      <Button onClick={handleGoHome} theme="primary">
+      <Button onClick={handleGoHome} type="primary">
         返回首页
       </Button>
     </Space>