Merge lane base check: develop 2e86525c0aa6

Merge lane base check: run the full gate on `develop` at `2e86525c0aa60c1e90215fea9ba456d293073f24` 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.

Base check develop 2e86525c0aa6: RED, reported develop_red. 9 tests fail: vitest (Tasks page write-verb affordances, automation wizard leave-guard) and api (test_exec_dashboard outcomes ×4, test_plan_engine switch labels). No PRs ejected.