Merge lane base check: develop d94848ff2cdb

Merge lane base check: run the full gate on `develop` at `d94848ff2cdb51467e8a9de6ff40707058713b82` 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 certified: full gate green on develop d94848ff2cdb (66986 passed, 0 failed). PR #7993 ejected as a conflict (merge_state dirty) and needs a rebase. Memory: none applied.