Context menus stay in view near the window edge; planes offer Create Sketch (#1398)

List menus open below-right of the cursor and flip to end at the cursor where they don't fit (shared context_menu::place / show for viewport, browser, toolbar and Select Other). Right-clicking a plane in the viewport, a construction plane row or an origin plane row (new menu with Create Sketch and Show/Hide) offers Create Sketch on that plane. Fixes #1354.

crates/ui-egui/src/browser.rs

@@ -859,6 +859,11 @@ fn origin_rows(app: &mut SolveApp, ui: &mut egui::Ui, depth: usize) {
                 app.session.visibility.hidden_origin.retain(|h| h != k);
             }
         }
+        if let Some(p) = r.secondary
+            && icon == "plane"
+        {
+            crate::context_menu::open_for(app, p, Target::OriginPlane { name: k.into() });
+        }
         if r.clicked
             && let Some(x) = sel
         {