Merge lane base check: develop 9da925d7d8d7

Merge lane base check: run the full gate on `develop` at `9da925d7d8d7068d863ddae60e934b01473f43b3` 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 9da925d red: test_shared_accounts_mount.py::test_a_current_cp_caches_the_list… fails (nodelinks.status.json not written, :964), fails every rerun; likely from 22d449c087 (Task 11441). develop_red reported. Memory: none applied