CRITICAL DISCOVERY: set_bone_global_pose_override() does NOT affect
the MeshInstance3D skinning pipeline. It only changes get_bone_global_pose()
return value. The actual skinning uses rest * pose * parent transforms.
The correct approach:
1. Stop AnimationPlayer (ap.stop() + ap.active = false)
2. Set local pose = rest_local_quat * offset_quat
3. This makes the final bone transform = rest * (rest * offset) = rest * offset
4. The skinning pipeline correctly uses this for vertex deformation
Also discovered: set_bone_pose_rotation() only works when AP is stopped.
When AP is active, it overwrites the local pose every frame.
Hermes
6e73fd7703