Merge lane base check: develop 85ff8d351c5f

Merge lane base check: run the full gate on `develop` at `85ff8d351c5f8974aae0373fa04dbe462988b477` alone and report it certified or red: nothing had certified it since the last attempt. A red verdict files a fix task; it never holds the lane. Filed by the control plane (`app/merge_lane.py::_certify_idle`). How: run `python3 tools/merge_lane.py run` once. It takes this check's batch, gates that commit with the full gate in its sandbox and reports `certified` or `develop_red` itself. Never run the gate by hand: a hand-run green reports nothing, so no certificate is recorded.

Base check develop 85ff8d351c5f: red, reported develop_red. Vale failed in run 1 and the CE release suite in both runs; both pass when run alone, so likely load-related flakes. The fix task is filed by the control plane.