Merge lane base check: develop 94ef394e2470

Merge lane base check: run the full gate on `develop` at `94ef394e24708701e560b274394392973dfa0116` 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.

develop 94ef394e24 red (reported develop_red): 2 jaahd vocabulary tests broke when 9af03ec026 moved fields into the ProjectSettingsFieldsIn mixin; same fix already on develop via #7407 (Task 11491), so no PR. Memory: none applied