Merge lane base check: develop ca65aa078085

Merge lane base check: run the full gate on `develop` at `ca65aa0780851dd0616121cbc3244c08d4f39de6` 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 ca65aa078085 certified: full gate green (57,501 passed, 0 failed, 678s), certified event reported by merge_lane.py run. Nothing merged or ejected; queue empty. Memory: none applied.