Merge lane base check: develop 58b3307079fa

Merge lane base check: run the full gate on `develop` at `58b3307079fa2f9b2855f12db96436a4a77fac14` 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 58b3307: RED (lane recorded develop_red). Only failure: e2e/nodevault-credentials.spec.ts:76 (NodeVault seal/untick→KMS) in frontend smoke, red after gate 3×; 56629 passed. Nothing queued, nothing merged/ejected. Memory: none applied.