feat: allow setting the die weight/mass

feat: die scaling

feat(demo): replace egui combobox with bevy UI dropdown

feat(demo): deduplicate button code

feat(demo): add bevy UI for throw and despawn

feat: allow setting the spawn position

feat: implement missing initial_rotation

feat(demo): don't prevent default event handling

feat(demo): naive toast system for results

feat: die id, print res in demo, visibility fixes

feat(demo): simplify lighting

feat: initial version with demo