Skip unnecessary rollback when reset never happened, show fallback
notice when AI commit message generation fails, and exit non-zero
when squash produces no changes.
Hoist mainBranch lookup before the new-commits check to avoid a
duplicate call, and report clearly when rollback itself fails so
the user knows to consult git reflog.
The old squash-merge workflow closed the branch, which made it
impossible to keep working after squashing. Now squash uses
git reset --soft to the merge base, preserving all changes as a
single commit on the current branch. Rolls back to the original
HEAD on failure.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Instead of squash-merging into main, `sandlot squash` now soft-resets
to the merge base and recommits, keeping the branch independent.
This removes the --force flag and all squash-merge logic from
mergeAndClose, which goes back to being a plain merge.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
