The mq list --ready command was filtering by issue.Type == "merge-request",
but beads created by `gt done` have issue_type='task' (the default) with
a gt:merge-request label. This caused ready MRs to be filtered out.
Changed to use beads.HasLabel() which checks the label, completing the
migration from the deprecated issue_type field to labels.
Added TestMRFilteringByLabel to verify the fix handles the bug scenario.
Fixes#816
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
4dd11d4ffa