Merge lane base check: develop 5bdca2892a5e

Merge lane base check: run the full gate on `develop` at `5bdca2892a5e9d3fd050e76849cfc6e8658199e5` 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 5bdca2892a5e RED (develop_red reported): 4 deterministic API unit failures — agent_bootstrap mac re-join, bitbucket git-token wire write_problem, doctrine golden (onboard prompts), persona onboard licence missing branch_prefix. Queue empty; nothing ejected.