Merge lane base check: develop 04a792568dad

Merge lane base check: run the full gate on `develop` at `04a792568dadcecba4d062b96fbd89492c52e205` 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 04a792568dad: RED, reported develop_red. 3 Playwright e2e failures (command-center:61, directory-split-width:65, project-edit-tabs:144) failed again in isolation. Nothing ejected; queue empty.