更新日志的中文说明

backend/app/core/logging.py

@@ -457,9 +457,9 @@ def setup_request_logging(app: FastAPI) -> None:
             elif response.status_code >= 400:
                 log_method = logger.warning
 
-            # 结构化访问日志
+            # 结构化访问日志（中文 message，方便直接阅读）
             log_method(
-                "request completed",
+                f"HTTP请求 {request.method} {request.url.path} → {response.status_code}（耗时{round(elapsed_ms, 2)}ms）",
                 extra={
                     "request_method": request.method,
                     "request_path": request.url.path,
@@ -497,7 +497,7 @@ def setup_request_logging(app: FastAPI) -> None:
         except Exception:
             elapsed_ms = (time.perf_counter() - started_at) * 1000
             logger.error(
-                "request failed",
+                f"HTTP请求异常 {request.method} {request.url.path}（耗时{round(elapsed_ms, 2)}ms）— 服务内部错误",
                 extra={
                     "request_method": request.method,
                     "request_path": request.url.path,