Merge lane base check: develop 490f227f2ace

Merge lane base check: run the full gate on `develop` at `490f227f2ace347da38b2e6ed2d5a8e8ec8f76c8` 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 490f227f2ace: RED (develop_red reported by merge_lane.py run). 3 failures in name-residue partition suite (tools/tests/test_check_name_residue.py), likely R1 rename #7078 vs name_residue.toml; 8920 passed. Nothing merged/ejected. Memory: used mem-26916.