- Added Codex-related fields to UserConfig and LLMConfig for managing OAuth tokens and model settings.
- Implemented Codex authentication endpoints and integrated them into the application.
- Enhanced LLMClient to support Codex as a valid provider, including token management and refresh logic.
- Updated UI components to include Codex configuration options and authentication status handling.
- Refactored environment variable utilities to accommodate Codex-specific settings.
