Merge lane base check: develop af62316fbe13

Merge lane base check: run the full gate on `develop` at `af62316fbe13069cbcf1b58e933ba4435a20db96` 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 af62316fbe13: develop_red (recorded by merge_lane.py run). 3 node-page e2e specs fail expectNoErrorBanner on "Failed to load sessions" (fixture misses the sessions read); 1 flake. Nothing merged. Memory: none applied.