Merge lane base check: develop 770870ab855e

Merge lane base check: run the full gate on `develop` at `770870ab855ebf5ea00f2c5e6aa121ae807cca96` 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 770870ab855e: develop_red recorded by merge_lane.py run. 56351 passed, 2 failed (test_host_platform_guard frozen-residual, test_virtual_nodes bootstrap byte-identical); both fail again alone. No PR; lane queue empty. Memory: none applied.