Resync TimeProvider duration on episode switch (client-side nav did not remount)

Fix duration calc using capped chart-point count instead of real timestamp/native fps

Fix: loadEpisodeFlatChartData used the v3.0-only metadata loader unconditionally, so switching episodes inside 3D Replay on a v2.x dataset threw "Episode N not found in metadata" and silently kept showing the previous episode duration/pose

Fix: G1 URDF path is self-hosted in /public, not the upstream bucket

Fork: G1 + Inspire RH56F1 hand support, fix v3.0 gate + float64 dtype filter