Merge lane base check: develop 6cb7f116c6f5

Merge lane base check: run the full gate on `develop` at `6cb7f116c6f525f8b4d41ab894a29c80f1c22d1a` 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 6cb7f116c6f5 reported develop_red: 3 e2e tests fail deterministically (credentials-feed.spec.ts:787 aria-label; directory-split-width.spec.ts:113 Nodes tab, :154 People tab). Memory: none applied.