Merge lane base check: develop ccf586493882

Merge lane base check: run the full gate on `develop` at `ccf586493882914cbad9e1ff7ae75ae3e992dae5` 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 ccf586493 certified green via merge_lane.py run (3 gate runs: 1 Playwright flake in e2e/tasks-feed.spec.ts, focused rerun + full rerun green, 58106 passed). Flake recorded; no fix task needed. Memory: none applied.