feat(select): orange hover / blue selection highlight for all objects

Solids (meshes) now tint on rollover and selection: hover washes orange,
selection washes blue, with selection winning when both apply. Meshes
re-upload their tint when the highlight set changes, and the rollover pick
now also hits shaded solid bodies and hatches (mirroring the click-select
order: wire → hatch → block hatch → solid).

Wires get the same scheme: the selection xray overlay recolours selected
entities blue and the hovered entity orange (previously both blue). Drops
the now-unused highlight_handles union helper and its cache.

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

src/app/update.rs

@@ -2639,8 +2639,28 @@ impl OpenCADStudio {
                     };
                     let view_proj = self.tabs[i].scene.camera.borrow().view_proj(bounds);
                     let all_wires = self.tabs[i].scene.hit_test_wires();
+                    // Mirror the click-selection pick order so the rollover
+                    // highlights every selectable object: wire → hatch →
+                    // block-internal hatch → shaded 3D solid body.
                     let hovered = scene::pick::hit_test::click_hit(p, &all_wires[..], view_proj, bounds)
-                        .and_then(|s| Scene::handle_from_wire_name(s));
+                        .and_then(|s| Scene::handle_from_wire_name(s))
+                        .or_else(|| {
+                            scene::pick::hit_test::click_hit_hatch(
+                                p,
+                                &self.tabs[i].scene.visible_hatches_for_click(),
+                                view_proj,
+                                bounds,
+                            )
+                        })
+                        .or_else(|| {
+                            scene::pick::hit_test::click_hit_insert_hatch(
+                                p,
+                                &self.tabs[i].scene.insert_hatches_for_click(),
+                                view_proj,
+                                bounds,
+                            )
+                        })
+                        .or_else(|| self.tabs[i].scene.mesh_click_hit(p, view_proj, bounds));
                     self.tabs[i].scene.set_hover_highlight(hovered);
                 } else {
                     // Suppress the rollover during a command or a drag.