[Feature] Dialogue users suggest adding user attribute mapping

### MaxKB Version

v2.2.0 

### Please describe your needs or suggestions for improvements

目前未开放 CAS 认证的用户属性映射，对话用户的用户名和姓名都是 CAS 平台的用户名

<img width="1651" height="496" alt="Image" src="https://github.com/user-attachments/assets/82417c39-c836-428c-827b-17af9db2d773" />

### Please describe the solution you suggest

建议添加CAS 平台用户属性映射

### Additional Information

_No response_