Merge lane base check: develop cc82b656df57

Merge lane base check: run the full gate on `develop` at `cc82b656df57ad0d26f176c2734d33fb6bfc59a3` 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 (Task 6722).

Base check: develop cc82b656df57 certified green via merge_lane.py run (tree 0802aebb06); hand cross-check of tools/check.sh also ok. Nothing merged or ejected; queue empty. Follow-up: lane gate parser reports 0 tests for node:test output.