Merge lane base check: develop fa54f82bccc7

Merge lane base check: run the full gate on `develop` at `fa54f82bccc7a3f7ec004db1916ac393752736e9` 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 fa54f82bccc7: certified green — full gate via merge_lane.py run, 656s, 56631 passed / 0 failed (tree 14bbcedf). Nothing merged or ejected; develop green. Memory: none applied.