Ellipse pie angles in Transform and Properties (#3451)

## Summary

Live ellipses already support pie start/end angles, canvas widgets and Invert Pie
like Illustrator. Label the Properties panel Transform section with Ellipse
Properties so the pie fields match the Transform panel and are easier to find.

## Tests

- `an_ellipse_shows_its_pie_properties` in `panels/transform` tests.

Closes storytold/vectorcraft#3451

Co-authored-by: nrq6993-a11y <nrq6993-a11y@users.noreply.github.com>

crates/ui-egui/src/panels/properties.rs

@@ -579,7 +579,10 @@ pub fn transform_section(app: &mut VectorcraftApp, ui: &mut Ui) {
         match &**live {
             vectorcraft_doc::LiveShape::Rectangle { .. } => corner_radius_row(app, ui, &n, "radius"),
             vectorcraft_doc::LiveShape::Polygon { .. } => super::transform::polygon_rows(app, ui, &n, live, "props-polygon"),
-            vectorcraft_doc::LiveShape::Ellipse { pie, .. } => super::transform::pie_rows(app, ui, *pie, "props-pie"),
+            vectorcraft_doc::LiveShape::Ellipse { pie, .. } => {
+                widgets::subheader(ui, tl!("Ellipse Properties:"));
+                super::transform::pie_rows(app, ui, *pie, "props-pie");
+            }
             _ => {}
         }
     }

crates/ui-egui/src/panels/transform.rs

@@ -505,6 +505,24 @@ mod tests {
         assert!(live(&app).polygon_sides_equal());
     }
 
+    /// #3451: a live ellipse shows pie start/end angles and Invert Pie in the Transform panel and
+    /// the Properties panel's Transform section; typed angles update the shape.
+    #[test]
+    fn an_ellipse_shows_its_pie_properties() {
+        let mut app = VectorcraftApp::new(vectorcraft_engine::Session::new(), Default::default());
+        app.run("file.new", json!({"width": 300, "height": 300})).unwrap();
+        app.run("shape.ellipse", json!({"x": 50, "y": 50, "width": 120, "height": 80})).unwrap();
+        for draw in [show as fn(&mut VectorcraftApp, &mut Ui), crate::panels::properties::transform_section] {
+            let shown = texts(&mut app, draw);
+            for t in ["Ellipse Properties:", "Pie Start Angle:", "0°", "Pie End Angle:", "360°", "Invert Pie"] {
+                assert!(shown.iter().any(|s| s == t), "{t} in {shown:?}");
+            }
+        }
+        app.run("object.setLiveShape", json!({"pieStart": 30, "pieEnd": 120})).unwrap();
+        let shown = texts(&mut app, show);
+        assert!(shown.iter().any(|s| s == "30°") && shown.iter().any(|s| s == "120°"), "{shown:?}");
+    }
+
     #[test]
     fn the_artboard_tool_shows_the_active_artboard() {
         let mut app = VectorcraftApp::new(vectorcraft_engine::Session::new(), Default::default());