Sketch free-form curves: Ellipse (centre, major axis end, minor radius), Fit Point and Control Point (degree 3 and 5) Splines, Conic Curve (rho); solved like other curves (points on them, tangency at shared ends, drag fit points), profiled as polylines; mirror/pattern/move/scale copy them; Tangent Arc continues splines and conics

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

crates/sketch/src/shape.rs

@@ -161,6 +161,7 @@ impl Sketch {
                 Seg2::Arc { center, radius, start, sweep } => Some(Shape::Round { c: center, r: radius, start, sweep }),
                 Seg2::Line { .. } => None,
             },
+            _ => None,
         }
     }
 }