Release v0.2.1

What's Changed

• Simplify release notes: use commit-based changelog
• Improve release notes: commit-based with PR enrichment
• Use GitHub built-in release notes generation
• Fix GitHub Models API endpoint for release notes
• Fix release notes: show API response for debugging
• Add AI-generated release notes via GitHub Models API

Full Changelog: v0.2.0...v0.2.1