- Updated clean-code skill with Robert C. Martin's Clean Code principles
- Refined content: naming, functions, comments, error handling, class design
- Fixed invalid heading format (## ## When to Use -> ## When to Use)
- Stabilized registry: use SOURCE_DATE_EPOCH for deterministic CI builds
- Improved catalog sorting for cross-environment consistency
- Regenerated all catalog and index files
Co-authored-by: jackjin1997 <jackjin1997@users.noreply.github.com>