feat: 前端适配后端新接口

适配后端统一模型 ID、协议字段、UUID 自动生成和结构化错误响应：

- 类型定义：Provider 新增 protocol 字段，Model 新增 unifiedId，CreateModelInput 移除 id
- API 客户端：提取结构化错误响应中的错误码
- 供应商管理：添加协议选择下拉框和表格列
- 模型管理：移除 ID 输入，显示统一模型 ID（只读）
- Hooks：错误码映射为友好中文消息
- 测试：所有组件测试通过，mock 数据适配新字段
- 文档：更新 README 说明协议字段和统一模型 ID

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

@@ -9,6 +9,7 @@ const mockProvider: Provider = {
   name: 'OpenAI',
   apiKey: 'sk-old-key',
   baseUrl: 'https://api.openai.com/v1',
+  protocol: 'openai',
   enabled: true,
   createdAt: '2024-01-01T00:00:00Z',
   updatedAt: '2024-01-01T00:00:00Z',
@@ -40,6 +41,7 @@ describe('ProviderForm', () => {
     expect(within(dialog).getByText('名称')).toBeInTheDocument();
     expect(within(dialog).getByText('API Key')).toBeInTheDocument();
     expect(within(dialog).getByText('Base URL')).toBeInTheDocument();
+    expect(within(dialog).getByText('协议')).toBeInTheDocument();
     expect(within(dialog).getByText('启用')).toBeInTheDocument();
     expect(within(dialog).getByPlaceholderText('例如: openai')).toBeInTheDocument();
     expect(within(dialog).getByPlaceholderText('例如: OpenAI')).toBeInTheDocument();
@@ -154,4 +156,41 @@ describe('ProviderForm', () => {
       expect(screen.getByText('请输入有效的 URL')).toBeInTheDocument();
     });
   }, 15000);
+
+  it('renders protocol select field with default value', () => {
+    render(<ProviderForm {...defaultProps} />);
+
+    const dialog = getDialog();
+    expect(within(dialog).getByText('协议')).toBeInTheDocument();
+  });
+
+  it('includes protocol field in form submission', async () => {
+    const onSave = vi.fn();
+    render(<ProviderForm {...defaultProps} onSave={onSave} />);
+
+    const dialog = getDialog();
+
+    // Get form instance and set values directly
+    const idInput = within(dialog).getByPlaceholderText('例如: openai') as HTMLInputElement;
+    const nameInput = within(dialog).getByPlaceholderText('例如: OpenAI') as HTMLInputElement;
+    const apiKeyInput = within(dialog).getByPlaceholderText('sk-...') as HTMLInputElement;
+    const baseUrlInput = within(dialog).getByPlaceholderText('例如: https://api.openai.com/v1') as HTMLInputElement;
+
+    // Simulate user input by directly setting values
+    fireEvent.change(idInput, { target: { value: 'test-provider' } });
+    fireEvent.change(nameInput, { target: { value: 'Test Provider' } });
+    fireEvent.change(apiKeyInput, { target: { value: 'sk-test-key' } });
+    fireEvent.change(baseUrlInput, { target: { value: 'https://api.test.com/v1' } });
+
+    const okButton = within(dialog).getByRole('button', { name: /保/ });
+    fireEvent.click(okButton);
+
+    // Wait for the onSave to be called
+    await vi.waitFor(() => {
+      expect(onSave).toHaveBeenCalled();
+      // Verify that the saved data includes a protocol field
+      const savedData = onSave.mock.calls[0][0];
+      expect(savedData).toHaveProperty('protocol');
+    }, { timeout: 5000 });
+  }, 10000);
 });