merge-squashbase

Squash and Rebase onto Main

1. Check current branch name and confirm with user
2. Do NOT create a worktree - work in the current directory
3. Run git fetch origin main
4. Run git rebase -i origin/main — in the editor, squash or fixup commits as appropriate, leaving one clean commit (or a small number of logical commits) with a descriptive message
5. If conflicts exist, list them and resolve one at a time preserving our branch's intent, running git rebase --continue after each
6. Run tests to verify
7. Push with git push --force-with-lease