* Add local OpenAI-compatible model discovery to /model
* Guard local OpenAI model discovery from Codex routing
* Preserve remote OpenAI Codex alias behavior
- Introduced environment variable CLAUDE_CODE_USE_GITHUB to enable GitHub Models.
- Added checks for GITHUB_TOKEN or GH_TOKEN for authentication.
- Updated base URL handling to include GitHub Models default.
- Enhanced provider detection and error handling for GitHub Models.
- Updated relevant functions and components to accommodate the new provider.
