Merge lane base check: develop afdd6fa3313a

Merge lane base check: run the full gate on `develop` at `afdd6fa3313a75fb707f938b6b3c22ff3bbc5f49` 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 afdd6fa3 red (develop_red reported): jaahd test_host_platform_guard fails, accounts.py has 1 '/proc/' above frozen 0, from Task 11287 (PR #7354) account Delete; route via host_platform. Nothing ejected; queue empty.