Merge lane base check: develop a70e3ad3de8c

Merge lane base check: run the full gate on `develop` at `a70e3ad3de8ce56158a7ac4a1a5d61399128b1bf` 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 a70e3ad3de8c red (reported develop_red): full gate failed the same way twice, on Mirror trees (strict), Community edition tooling suite, Org transfer rule tables and NodeVault interop guard (7 of 9923 tests). No PR.