RigidBench: simulator-grounded evaluation data for rigid-body physics in video generation

100-sample evaluation set for measuring physical fidelity in image-to-video generation models. Pairs photorealistic Cycles renders with simulator-exact per-frame ground truth: per-actor masks, per-pixel depth, per-actor 6-DoF trajectories, and per-frame contact events. Covers five rigid-body tasks (free fall, bounce, ramp collision, ball chain, drop into cluster) across four distribution-shift splits. See the included README for the file layout and loading code.