Merge lane base check: develop 4f45c36dfe10

Merge lane base check: run the full gate on `develop` at `4f45c36dfe10b05a98f5091ff8ba6cdb0898462c` 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 on develop 4f45c36dfe10: develop_red, reported by merge_lane.py run (full gate red twice). Only the API unit stage failed: 47 tests across trigger_intake, triggers_routes, workflows_routes, token_billing, virtual_nodes. Queue empty; nothing merged or ejected. Memory: none applied.