Feature: 用户进退群事件 intent

[ACaiCat]

#206

试了可以正常收到事件，可能是ws的也上线或者灰度了

06-28 17:50:37 [SUCCESS] nonebot | QQ xxx | [EventType.GROUP_MEMBER_REMOVE]: {'event_id': 'GROUP_MEMBER_REMOVE:xxx', 'timestamp': datetime.datetime(2026, 6, 28, 9, 50, 34, tzinfo=TzInfo(0)), 'group_openid': 'xxx', 'member_openid': 'xxx'}

06-28 17:50:49 [SUCCESS] nonebot | QQ xxx | [EventType.GROUP_MEMBER_ADD]: {'event_id': 'GROUP_MEMBER_ADD:xxx', 'timestamp': datetime.datetime(2026, 6, 28, 9, 50, 46, tzinfo=TzInfo(0)), 'group_openid': 'xxx', 'member_openid': 'xxx'}