refactor: 全局适配 ApiFamily/EndpointKind 结构化标识体系

将新的 (ApiFamily, EndpointKind) / `family:kind` 签名体系应用到整个代码库：
- API Handlers: 所有 adapter/handler 使用新的签名格式
- Services: provider, model, usage, cache, auth 等服务层适配
- Database: ProviderEndpoint 新增 api_family/endpoint_kind 字段
- Frontend: Provider 管理、Usage 表格等组件适配
- Tests: 更新所有相关测试用例

src/core/vertex_auth.py

@@ -163,7 +163,9 @@ class VertexAuthService:
 
         except httpx.HTTPStatusError as e:
             error_body = e.response.text[:500] if e.response.text else "(empty)"
-            raise VertexAuthError(f"Failed to get access token: HTTP {e.response.status_code}: {error_body}")
+            raise VertexAuthError(
+                f"Failed to get access token: HTTP {e.response.status_code}: {error_body}"
+            )
         except Exception as e:
             raise VertexAuthError(f"Failed to get access token: {e}")