Merge lane base check: develop cfc990df770a

Merge lane base check: run the full gate on `develop` at `cfc990df770a351dfe7641b93ed1425fba4da0e8` 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 @ cfc990df770a certified: full gate green (62,032 passed, 0 failed); nothing ejected. Memory: none applied