rlmesh_rotation_transform_new
Callable identity survives cloning; hashes are process-local. NULL equals NULL and hashes to 0.
RLMeshStatus rlmesh_rotation_transform_new(
RLMeshRotationTransformFn fn,
void* user_data,
void (*free_user_data)(void* user_data),
RLMeshRotationTransform** out
)