Merge lane base check: develop 8ae5b1989404

Merge lane base check: run the full gate on `develop` at `8ae5b1989404a747de7875fcfe3f2fa5fb949e88` 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.

develop @ 8ae5b1989404 passed the full gate and was reported certified (61,922 tests passed, 0 failed). Nothing was ejected. Memory: none applied.