When path_type == Spline, the leader line is now tessellated as a
Catmull-Rom spline through the bend points (8 segments per span)
instead of connecting them with straight segments. Straight/Invisible
path types are unchanged. Key vertices and tangent geoms still use the
raw control points for snap and tangent snapping.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>