Merge lane base check: develop d584e1fae53f

Merge lane base check: run the full gate on `develop` at `d584e1fae53f445edd5b57f317607a07c38aefc3` 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.

Base check develop d584e1fae53f: RED (lane reported develop_red). Full gate: 4 API unit failures; 2 reproduce in isolation (data_access_events/durable_enqueue/support_comments/tenant_gmail set). Fix task is CP-filed; lane not held. Memory: none applied