Support same model naming convention as github copilot in vscode

[princeatoss]

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