UserInfoEndpoint missing create userinfo response method

UserInfoEndpoint missing create userinfo response method: a task in harbor-swesmith-rl-artifacts: Harbor SWE-Smith 强化学习数据产物 (Harbor dataset). The UserInfoEndpoint class is missing the create userinfo response method, causing AttributeError when trying to call it.

The task

The `UserInfoEndpoint` class is missing the `create_userinfo_response` method, causing `AttributeError` when trying to call it.

Part of keryszhan/harbor-swesmith-rl-artifacts.