refactor: 优化活跃请求状态查询逻辑

- 重命名 get_active_requests 为 get_active_requests_status
- 支持从端点配置读取超时时间
- 新增 content_length_limit 错误类型

src/api/admin/usage/routes.py

@@ -660,7 +660,7 @@ class AdminActiveRequestsAdapter(AdminApiAdapter):
             if not id_list:
                 return {"requests": []}
 
-        requests = UsageService.get_active_requests(db=db, ids=id_list)
+        requests = UsageService.get_active_requests_status(db=db, ids=id_list)
         return {"requests": requests}