ApiKey 长度限制导致Minimax 模型不能正常添加

### Pre-checks

- [x] I have searched [existing issues](https://github.com/dataelement/Clawith/issues) and this is not a duplicate.

### Deployment Method

Docker

### Steps to Reproduce

由于Minimax的APIKey很长，api_key_encrypted限制了500长度，无法正常保存

### Expected vs Actual Behavior

Minimax 模型正常添加保存

### Logs / Screenshots

_No response_