Merge lane base check: develop 7859c2a8f406

Merge lane base check: run the full gate on `develop` at `7859c2a8f406662007dba16833c6404cc23c338f` 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).

Base check develop 7859c2a8f406: RED (lane reported develop_red; full gate ran twice, 8757 tests passed, 3 failed). Failing: mirror sensitive ratchet, community edition suite, mirror sensitive-content. Cause: PR #7101 (Task 10528) adds packaging/jaahd-update.sh refs in node_log_history.py, so the count is above the baseline. Queue empty; nothing merged or ejected.