Ellipse dimensions: major radius (type major: centre to axis end) and minor radius (a radius dimension on the ellipse)

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

crates/sketch/src/model.rs

@@ -647,6 +647,8 @@ impl Sketch {
                 need_line(a)?;
                 need_line(b)?;
             }
+            // On an ellipse, a radius dimension holds its minor radius.
+            Radius { c, .. } if matches!(self.curves.get(c).map(|x| &x.kind), Some(CurveKind::Ellipse { .. })) => {}
             Radius { c, .. } | Diameter { c, .. } => need_round(c)?,
             Concentric { a, b } => {
                 need_round(a)?;