Merge lane base check: develop c80974003c30

Merge lane base check: run the full gate on `develop` at `c80974003c3090946a30fdb011b98425148bb03b` 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 c80974003c30 certified: full gate tools/check.sh green (194/194 tests, static sanity ok), certificate 01a16e5d posted. Gated by hand since repo has no tools/merge_lane.py. Queue empty. Memory: used mem-5, mem-6; proposed none.