Merge lane base check: develop 187c9ee418ea

Merge lane base check: run the full gate on `develop` at `187c9ee418eaa379bbdd659bd86bff2f67435f6f` 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 (Task 6722).

Base check develop 187c9ee: develop_red (reported by merge_lane.py run). Full gate 58,948 passed, 2 failed, both reproduce alone: test_jaah_extension_spec::test_the_file_is_the_table_projection, test_jira_routes::test_a_dangling_credential_id_is_409_not_a_500. Nothing merged. Memory: none applied.