examples/: upgraded ReactWindowDataset (adds motion filter to catch operator-paused windows the bad_frames check cant); canonical self-contained demo_react_window.py (no twm dependency); new examples/README.md with four-filter explanation and recipes per use case

Bake ot_loss intervals into bad_frames.json (47 events, rotation-aware detector); dataloader skips them; docs/quality + caveats updated; data_quality_breakdown #3 renamed sensor_at_rest → ot_loss

Add example dataloader: ReactWindowDataset for short contact-rich window sampling + demo (static grid + GIF) with sensor-frame overlay