refactor: 迁移 UI 组件库从 Ant Design 至 TDesign

- 替换 antd 为 tdesign-react 作为主要 UI 组件库
- 引入 Recharts 替代 @ant-design/charts 实现图表功能
- 移除主题系统相关代码（ThemeContext、themes 目录）
- 更新所有组件以适配 TDesign 组件 API
- 更新测试用例以匹配新的组件实现
- 新增 TDesign 和 Recharts 集成规范文档

frontend/src/__tests__/components/ProviderForm.test.tsx

@@ -22,7 +22,12 @@ const defaultProps = {
 };
 
 function getDialog() {
-  return screen.getByRole('dialog');
+  // TDesign Dialog doesn't have role="dialog", use class selector
+  const dialog = document.querySelector('.t-dialog');
+  if (!dialog) {
+    throw new Error('Dialog not found');
+  }
+  return dialog;
 }
 
 describe('ProviderForm', () => {
@@ -122,7 +127,8 @@ describe('ProviderForm', () => {
     render(<ProviderForm {...defaultProps} loading={true} />);
     const dialog = getDialog();
     const okButton = within(dialog).getByRole('button', { name: /保/ });
-    expect(okButton).toHaveClass('ant-btn-loading');
+    // TDesign uses t-is-loading class for loading state
+    expect(okButton).toHaveClass('t-is-loading');
   });
 
   it('shows validation error for invalid URL format', async () => {