Merge lane: jaah

Merge lane run: batch the queued PRs, run the full gate (if any) once on their merged tree, and merge the batch when it is green. Filed by the control plane (`app/merge_lane.py::ensure_lane`).

Merged PR #5810 (Task 7088, e2e tenant-isolation expects /no-access) into develop at 8df45b7e after a green quick gate on the merged tree (5752 passed). Nothing ejected; queue empty; develop not flagged red.