Merge lane base check: develop a02c80a61499

Merge lane base check: run the full gate on `develop` at `a02c80a614992d78212e14c22a68e8191983159e` 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 a02c80a61499 certified green: merge_lane.py run full gate exit 0 in 1127s, 59884 passed/0 failed. Nothing merged or ejected. Memory: none applied.