Merge lane base check: develop f7e659e7de10

Merge lane base check: run the full gate on `develop` at `f7e659e7de107e3db601c78d4b39d10dd8e2d5bd` 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 f7e659e7de10 certified: full gate green (66493 passed, 0 failed); nothing ejected, develop not red.