Add 20 dataloader sample-window GIFs (random windows from post-trim ReactWindowDataset) for visual ot_loss verification

Visualization refactor (twm/viz.py single source); native 1280x480 + left|middle|right cam order; freeze_diagnose/ replaces freeze_check/ and freeze_classify/; finding: all freezes are recording-pipeline stalls

Fix RealSense BGR→RGB; sample_window.gif now matches recording-viewer layout

Regen previews at 256-color palette; 3-cam dataloader gif; add docs/curation_pipeline.md

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