style(backend): formatter 收口两处漏网文件（纯格式无行为变化）

Co-Authored-By: Claude Code <noreply@anthropic.com>

backend/app/services/rating_service.py

@@ -217,7 +217,10 @@ def update_grade(
             raise NotFoundError("评级等级不存在")
 
         _ensure_no_overlap(
-            rating_repository.list_all(session, for_update=True), new_min, new_max, exclude_id=grade_id
+            rating_repository.list_all(session, for_update=True),
+            new_min,
+            new_max,
+            exclude_id=grade_id,
         )
         existed = rating_repository.get_by_name(session, payload.grade_name)
         if existed is not None and existed.id != grade_id: