Merge lane base check: develop 54b42b773214

Merge lane base check: run the full gate on `develop` at `54b42b7732145fea3d5673180ac59b2dd33421f6` 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 54b42b773 RED (gate 2×, 4 failed): node_platform.py:175 names infra/local/Dockerfile.api, absent from jaah-ce mirror → Mirror trees + CE tooling + mirror-sensitive suites fail. Culprit ccd3d3dc8 (Task 11107, PR #7273). Memory: none applied