Merge lane base check: develop 6ab085cf462e

Merge lane base check: run the full gate on `develop` at `6ab085cf462e15842767b8d1044a02565c805d36` 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 6ab085cf462e is red: Mirror trees (strict), CE tooling suite and Mirror sensitive-content failed in the lane sandbox on both runs; they pass outside it. Lane reported develop_red, fix task #10802 filed. Memory: none applied