Fix hand joint order in observation.state to match actual Pink-IK action term (find_joints without preserve_order uses raw articulation order, not the real-dataset side-grouped convention)

Fix observation.state: 57-dim -> 28-dim, matches action joint ordering exactly

Add batch02 (12 successful demos) -- 16 episodes total

Add 4 successful G1 Dex3 cube-stacking demos (LeRobot format, rendered cameras)

initial commit