Function rotation_zup_to_yup 

pub(crate) fn rotation_zup_to_yup(rotation_zup: &[f64; 9]) -> [f32; 9]

Conjugate a Z-up rotation into the Y-up wire frame: P * R * P^T. The swap is linear (zup_to_yup), so this is the same identity mesh_to_yup_in_place relies on for positions/origin, applied to a 3x3 instead of a 3-vector.