Exact profiles for splines of any degree (a degree-4…7 Bézier segment kind, Seg2::Bezier, extruded as B-spline edges) and for free-form curves cut by crossings (exact sub-curves whose ends are moved to the true crossing, found by Newton; polylines only where that fails)

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

crates/kernel/src/freeform.rs

@@ -1,4 +1,4 @@
-//! Free-form profile edges: cubic Béziers as B-spline curves and conics as rational quadratic
+//! Free-form profile edges: Béziers (cubic and higher) as B-spline curves and conics as rational quadratic
 //! NURBS curves (exact ellipses, parabolas and hyperbolas from sketches).
 
 use solvecraft_geom::{Plane, Seg2};
@@ -20,6 +20,10 @@ pub(crate) fn edge(plane: &Plane, s: &Seg2, a: &mt::Vertex, b: &mt::Vertex) -> O
             let curve = mt::NurbsCurve::new(mt::BSplineCurve::new(mt::KnotVec::bezier_knot(2), ctrl));
             Some(mt::Edge::new(a, b, mt::Curve::NurbsCurve(curve)))
         }
+        Seg2::Bezier { n, ref p } => {
+            let inner = p.get(1..(n as usize).clamp(1, solvecraft_geom::MAX_BEZIER_DEGREE))?;
+            Some(mt::builder::bezier(a, b, inner.iter().map(|q| p3(plane.to_world(*q))).collect()))
+        }
         Seg2::Line { .. } | Seg2::Arc { .. } => None,
     }
 }