Function prt_compute_both_oriented 

pub fn prt_compute_both_oriented(
    c_xy: &[u8],
    c_sw: &[u8],
    xy_is_primary: bool,
) -> (Vec<u8>, Vec<u8>)

PRT with orientation handling

Given c_xy at node (x,y) layer z, and c_sw at node (z_y,y) layer z_sw:

• If xy_is_primary (x < z_y): c_xy is C, c_sw is C*
• Otherwise (x > z_y): c_xy is C*, c_sw is C

Returns

Tuple of (u_xy, u_sw) - U values for each node at their respective layers