Merge lane base check: develop bd4848d1a3eb

Merge lane base check: run the full gate on `develop` at `bd4848d1a3eb029223b9510626932967f9a1034f` 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 bd4848d1a3eb: develop_red (reported by merge_lane.py run). 2 failures: jaahd + platform bundle selftests — Dependabot c329d6a2e pins websockets==17.3 but apps/jaahd/vendor holds 17.2. Nothing merged/ejected. Memory: none applied.