Merge lane base check: develop f00566e490b2

Merge lane base check: run the full gate on `develop` at `f00566e490b29c614a061f61d8760c490b601306` 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 f00566e490b2 certified green: the full gate passed on retry after one flaky API unit test, which passed in isolation. Nothing ejected; no fix task needed.