Merge lane base check: develop 1f6a72d1d949

Merge lane base check: run the full gate on `develop` at `1f6a72d1d9490d5bb4ff5e0c94131c55fd90ef5a` 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 1f6a72d1d949 RED (develop_red reported): test_an_anchor_whose_push_arrives_late_is_not_a_rollback is a time bomb — fixed _T0=2026-11-01 vs wall-clock received_at past the 24h PARTIAL_RECOMPUTE_FOR window; not a merge regression (fails pre-#7720 too).