Replace MergeNoFF with MergeSquash in the Refinery to preserve the original
conventional commit message (feat:/fix:) from polecat branches instead of
creating "Merge polecat/... into main" commits.
Changes:
- Add MergeSquash function to internal/git/git.go
- Add GetBranchCommitMessage helper to retrieve branch commit messages
- Update engineer.go doMerge to use squash merge with original message
Fixes#855
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
d67aa0212c