Merge lane base check: develop c7785fb9b312

Merge lane base check: run the full gate on `develop` at `c7785fb9b312519a6ccdea032e98b0a5dd023f81` 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).

develop c7785fb9b312 certified: full gate green via merge_lane.py run (58598 passed, 0 failed, 890s); certified event recorded. Nothing merged or ejected. Memory: none applied.