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 7 PRs (#6076, #6075, #6077, #6078, #6032, #6080, #6031) in 2 quick-gated batches; ejected 0; queue empty. develop 011061a09 green: the stale develop_red record (c2ad8614: Vale, ast-grep) passes on the current tip.