Sketch: associative, editable sketch patterns (#1103)

Rectangular and circular sketch patterns stay linked to their source: editing the pattern's count, spacing or the source geometry updates the copies, and the copies keep their point and radius relations. Patterns are saved under format 20; older designs keep their independent copies.

crates/ui-egui/src/viewport.rs

@@ -2214,7 +2214,11 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
             }
         }
         // Double-click a dimension: edit its value in place.
-        let dim_edit = resp.double_clicked() && !held && app.tool.is_none() && app.dialog.is_none() && crate::dim_view::double_click(app, p);
+        let dim_edit = resp.double_clicked()
+            && !held
+            && app.tool.is_none()
+            && app.dialog.is_none()
+            && (crate::sketch_modify_ui::double_click_pattern(app, p) || crate::dim_view::double_click(app, p));
         // Double-click a text (an outline or inside a letter; the first click selected it): edit it.
         if resp.double_clicked()
             && !held