Merge lane base check: develop 27e1574088c0

Merge lane base check: run the full gate on `develop` at `27e1574088c016d1b024f6914f39bee376bfe089` 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 of develop 27e1574088c0: certified. The full gate passed in 783s (61185 tests passed, 0 failed). No PRs ejected; develop is green. Memory: none applied.