refactor: 重构模型测试错误解析逻辑并修复用量统计变量引用

- 将 ModelsTab 和 ModelAliasesTab 中重复的错误解析逻辑提取到 errorParser.ts
- 添加 parseTestModelError 函数统一处理测试响应错误
- 为 testModel API 添加 TypeScript 类型定义 (TestModelRequest/TestModelResponse)
- 修复 endpoint_checker.py 中 usage_data 变量引用错误

frontend/src/api/endpoints/providers.ts

@@ -61,12 +61,34 @@ export async function deleteProvider(providerId: string): Promise<{ message: str
 /**
  * 测试模型连接性
  */
-export async function testModel(data: {
+export interface TestModelRequest {
   provider_id: string
   model_name: string
   api_key_id?: string
   message?: string
-}): Promise<any> {
+  api_format?: string
+}
+
+export interface TestModelResponse {
+  success: boolean
+  error?: string
+  data?: {
+    response?: {
+      status_code?: number
+      error?: string | { message?: string }
+      choices?: Array<{ message?: { content?: string } }>
+    }
+    content_preview?: string
+  }
+  provider?: {
+    id: string
+    name: string
+    display_name: string
+  }
+  model?: string
+}
+
+export async function testModel(data: TestModelRequest): Promise<TestModelResponse> {
   const response = await client.post('/api/admin/provider-query/test-model', data)
   return response.data
 }