Merge lane base check: develop 9016537c56e3

Merge lane base check: run the full gate on `develop` at `9016537c56e3fbf47782b5ebb1c0d3d2c8931564` 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 9016537c56e3 certified: the full gate passed in the merge-lane sandbox (64,763 tests passed, 0 failed); queue empty. Memory: none applied.