Merge lane base check: develop 57009dc0f171

Merge lane base check: run the full gate on `develop` at `57009dc0f171555c3dd85242f2eb2da940ec97f6` 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`).

develop@57009dc0f RED (mypy: durable record dropped its verdict + migration typing; Vale; vitest 8208/8213 fixture drift; bootstrap golden/user-data headroom from 8237). Fixed forward in PR #6379, merged 528e30daf; full gate green, Jaah Deploy success. Memory: none applied.