New bin/release script that automates the full release process:
- Major releases: creates branch, generates changelog, updates version,
creates GitHub release, triggers Docker build, opens changelog PR
- Patch releases: same flow on existing release branch
- Individual subcommands for testing each step independently
Removes bin/release_manager.py and bin/get_changes.py which used an
older RC-based release workflow.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
