Add a release helper that turns a Git commit range into grouped release-note draft content for OSS maintainers.
Acceptance criteria:
- Accept a base ref and head ref.
- Group changes by docs, fixes, features, tests, and maintenance when possible.
- Include warnings for untagged releases or dirty worktrees.
- Do not publish or tag automatically.
Add a release helper that turns a Git commit range into grouped release-note draft content for OSS maintainers.
Acceptance criteria: