Kernel: concave edge fillets; whole smooth-loop blends of planar faces (cylinders and tori: pocket floors, plate outlines); rounding every edge of a convex planar body (sphere corners); healing after booleans (exact lines/arcs for intersection curves, coplanar faces merged, collinear edges joined); faces rebuilt on their stored surfaces

Oracle: 28/29.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/kernel/src/build.rs

@@ -609,7 +609,7 @@ fn cubic_basis(knots: &[f64], n_ctrl: usize, u: f64) -> Vec<f64> {
 }
 
 /// Cubic B-spline through points at uniform parameters (clamped, knots by averaging).
-fn interpolate_cubic(pts: &[Vec3]) -> Option<mt::BSplineCurve<mt::Point3>> {
+pub(crate) fn interpolate_cubic(pts: &[Vec3]) -> Option<mt::BSplineCurve<mt::Point3>> {
     let m = pts.len();
     if m < 4 {
         return None;