Merge lane base check: develop 8627cc965698

Merge lane base check: run the full gate on `develop` at `8627cc965698baee35f1648e2d395e1eb0425f40` 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 8627cc9: red (jaahd verb-contract test, already fixed by #7000). Fixed forward a docs-build red, merged #7006; develop deploy 40346109028 green. PR #7010 is redundant with #7004 and left open unmerged. Ejected nothing. Memory: proposed 1 gotcha.