Previously gt done wrote MRs to .beads/mq/*.json files, but gt mq list
queried beads for issue_type=merge-request. These were two different
storage systems, so MRs created by gt done never showed in gt mq list.
Now gt done creates a proper MR bead with:
- issue_type: merge-request
- Description containing branch, target, source_issue, rig, worker
Also updated mq_submit.go for consistency.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>