Support same model naming convention as github copilot in vscode

### Describe the bug

Currently, cli naming convention for models is different than vscode github copilot or claude code itself

### Affected version

1.0.22

### Steps to reproduce the behavior

1. in any agent, for model use name: opus
2. in cli, use /agent
3. you will see a warning message model "opus" is not available; will use current model instead

### Expected behavior

Support naming model same as github copilot in vscode

### Additional context

_No response_