Carry hatch origin through creation and pattern editing

src/scene/mod.rs

@@ -3794,6 +3794,7 @@ impl Scene {
         let ((x0, y0), (x1, y1)) = self.paper_limits()?;
         let (x0, y0, x1, y1) = (x0 as f32, y0 as f32, x1 as f32, y1 as f32);
         Some(HatchModel {
+            pattern_origin: None,
             render_instance: None,
             world_origin: [0.0, 0.0],
             boundary: Arc::new(vec![[x0, y0], [x1, y0], [x1, y1], [x0, y1], [x0, y0]]),