Add commit-based release notes generation to GitHub releases.
This PR updates the release workflow to generate release notes from git commits instead of extracting from CHANGELOG.md. The new system:
- Automatically detects the previous tag for comparison
- Categorizes commits using conventional commit types
- Includes commit hashes and contributor statistics
- Handles first release scenario gracefully
Related: #362 (test architecture refactoring)
Conceived by Romuald Członkowski - www.aiadvisors.pl/en
