Merge lane base check: develop 0c474ec4b93e

Merge lane base check: run the full gate on `develop` at `0c474ec4b93eee110b0c2fa7b4d58ac8c3fe969d` 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).

develop 0c474ec4b93e certified: merge_lane.py run full gate green in 674s (56,570 passed, 0 failed), tree e60962ea. Nothing merged or ejected; no fix task needed. Memory: none applied.