Merge lane base check: develop ea97aeec43d8

Merge lane base check: run the full gate on `develop` at `ea97aeec43d858aa763b92384bf7be44b578059b` 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.

Base check of develop ea97aeec43d8: full gate green, 61497 passed and 0 failed; the lane recorded it as certified. Nothing ejected; develop green.