Merge lane base check: develop d30ff0e1858b

Merge lane base check: run the full gate on `develop` at `d30ff0e1858bbeec8a1d7be82e51a7cca3c2b432` 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 d30ff0e certified green — merge_lane.py run full gate passed in 682s (57,823 tests, 0 failed); event=certified reported. Nothing merged or ejected; queue empty. Memory: none applied.