CeTZ 0.5.2 requires 3D coordinate vectors (x, y, z) for raw
coordinate tuples passed to coordinate.resolve(). Update internal
wire computations (dodge, guided) to use 3-element tuples, fix
.last() to .at(1) for y-component access on resolved coordinates,
and add a normalize-coord utility that automatically pads user-
provided 2D points (x, y) to (x, y, 0) so users do not need to
specify the z dimension.
