feat(statusbar): highlight cycling-list object on row hover

Add a scene hover_highlight handle that renders an entity with the
selection colour without joining the real selection. The cycling list
box sets it on row enter / clears on exit, so hovering a row glows the
matching object in the drawing.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/app/mod.rs

@@ -767,6 +767,8 @@ pub enum Message {
     ToggleSelectionCycling,
     /// Add an object from the selection-cycling list box to the selection.
     CycleSelect(acadrust::Handle),
+    /// Preview (highlight) a cycling-list row's object, or clear with `None`.
+    CycleHover(Option<acadrust::Handle>),
     /// Dismiss the selection-cycling list box without picking.
     CycleCancel,
     /// Toggle the selection-filter type picker open/closed.

src/app/update.rs

@@ -3631,19 +3631,27 @@ impl OpenCADStudio {
             Message::ToggleSelectionCycling => {
                 self.selection_cycling ^= true;
                 self.cycle_candidates = None;
+                self.tabs[self.active_tab].scene.set_hover_highlight(None);
                 Task::none()
             }
             Message::CycleSelect(handle) => {
                 // Add the picked object to the current selection (accumulate).
                 self.cycle_candidates = None;
                 let i = self.active_tab;
+                self.tabs[i].scene.set_hover_highlight(None);
                 self.tabs[i].scene.select_entity(handle, false);
                 self.tabs[i].scene.expand_selection_for_groups(&[handle]);
                 self.refresh_properties();
                 Task::none()
             }
+            Message::CycleHover(handle) => {
+                let i = self.active_tab;
+                self.tabs[i].scene.set_hover_highlight(handle);
+                Task::none()
+            }
             Message::CycleCancel => {
                 self.cycle_candidates = None;
+                self.tabs[self.active_tab].scene.set_hover_highlight(None);
                 Task::none()
             }
             Message::ToggleSelectionFilterPopup => {