Merge lane base check: develop bc16e4973da4

Merge lane base check: run the full gate on `develop` at `bc16e4973da4b8639f2979d6dc9557ae1b2231db` 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 bc16e4973da4: develop_red recorded. 2 billing tests fail because POST /api/billing/orgs/{org_id}/trial (b07806837, Task 8913) has no authz-matrix row and no registered console action. Gate took 578s. Nothing merged, nothing ejected. Memory: none applied.