Bound Process payload sizes and capture rendered order feedback

Box the optional Process menu context and changed order command without changing identity or command semantics. Add opt-in actual WGPU readbacks to the split-event OA/SA reorder evaluator. Strict all-target lint, format and affected desktop paths pass; native acceptance follows.

crates/oa-desktop/src/app/process_multiselect/tests.rs

@@ -602,7 +602,7 @@ fn menu(app: &mut App, target: Target, label: &str) -> Message {
         _ => panic!("This fixture opens contribution menus"),
     };
     let mut request = model_menu::Request::object(object, iced::Point::new(180., 150.));
-    request.process = app.topology_context();
+    request.process = app.topology_context().map(Box::new);
     request.selection_target = Some(Box::new(target));
     let _ = app.update(Message::Menu(model_menu::Event::Open(request)));
     let opened = app
@@ -610,7 +610,10 @@ fn menu(app: &mut App, target: Target, label: &str) -> Message {
         .as_ref()
         .expect("Captured Process menu must survive the open epoch change");
     assert!(opened.valid(app));
-    assert_eq!(opened.request.process, app.topology_context());
+    assert_eq!(
+        opened.request.process.as_deref().copied(),
+        app.topology_context()
+    );
     model_menu::popup(app)
         .unwrap()
         .entries