Merge lane base check: develop 448f9b39d6c1

Merge lane base check: run the full gate on `develop` at `448f9b39d6c105bb234e120633011541c5bdf483` 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 448f9b39d6c1: develop_red (reported by merge_lane.py run). 56780 passed, 1 failed, reproduced in a focused rerun: test_cross_org_isolation::test_every_path_parameter_is_swept_or_named — new {key_id} (API keys, Task 9369) neither seeded nor in _UNSEEDED_PARAMS. Nothing merged. Memory: none applied.