* chore: add script to clean up worktrees with merged PRs Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> * fix: use safe arithmetic to avoid set -e exit on zero increment Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>