fix: remove "--" from XML comments (forbidden by the XML spec)

fix(assets): hand_track prop physics — mass refit on 4 props + tennis-ball restitution

fix(box_task): re-fit cardboard_box visual walls to its frozen collision hull (#29)

Add IsaacSim USDs: box/gso container props + material-fixed kettle_matfix/meshycup_mat/board_nail_mat

Duplicate from SomaStacksOrg/roboverse_data