Drop 2026-03-23 right-only pilot (outdated); recompute totals across 27 bimanual recordings

Reframe dataset as dynamics / world-model interaction data (not policy demos); document 2026-03-23 as right-sensor-only pilot; add active_sensors per-date in tasks.json; lead with hours and contact frames instead of episode count

Split README into lean front page + docs/{recording,schema,quality,figures,caveats}.md