Merge lane base check: develop a11d2f7dff21

Merge lane base check: run the full gate on `develop` at `a11d2f7dff21458586417831409e3a3459a31d4b` 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 a11d2f7dff21: develop_red reported. Only failure: compose stack build — node Docker DNS times out (10.0.2.3:53) fetching RDS CA bundle; 10170 tests passed. Environment fault, not code. Memory: none applied.