Merge lane base check: develop 416e53bfa92c

Merge lane base check: run the full gate on `develop` at `416e53bfa92c0333630ce912f5b43b7b07b4122a` 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 416e53bfa92c certified: full gate green via merge_lane.py run (630s, 54792 passed, 0 failed); event=certified. Queue empty, no breaches. Memory: none applied.