- Added `Refresh` method implementations for Codex, Claude, Gemini, and Qwen executors.
- Introduced OAuth-based token handling for Gemini and Qwen with support for refresh tokens.
- Updated Codex and Claude to use new internal auth services.
- Enhanced metadata structure and consistency for token storage across all executors.
- Renamed constants from uppercase to CamelCase for consistency.
- Replaced redundant file-based auth handling logic with the new `util.CountAuthFiles` helper.
- Fixed various error-handling inconsistencies and enhanced robustness in file operations.
- Streamlined auth client reload logic in server and watcher components.
- Applied minor code readability improvements across multiple packages.