跨域bug修复2

backend/services/student_service.py

@@ -119,15 +119,12 @@ class StudentService:
     @staticmethod
     async def get_ranking(
         user_id: int,
-        class_id: Optional[int] = None,
         limit: int = 50
     ) -> Dict[str, Any]:
         """获取排行榜（单班级系统）"""
-        # 单班级系统，直接获取排行榜
         ranking = await StudentModel.get_ranking(limit=limit)
         
         return {
-            "class_id": class_id or 1,
             "ranking": ranking
         }