Merge lane base check: develop dea1e4bae993

Merge lane base check: run the full gate on `develop` at `dea1e4bae993d5a6671958af7370e38d3b33c8cd` 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 dea1e4bae993 certified green: full gate passed (59,944 tests, 0 failed). No PRs ejected, queue empty. Memory: none applied.