fix(editor): improve button colors for visible hover/active feedback

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

examples/editor_demo/src/main.rs

@@ -127,6 +127,7 @@ impl ApplicationHandler for EditorDemoApp {
                 // Begin UI frame
                 state.ui.begin_frame(mx as f32, my as f32, mouse_down);
 
+
                 // Draw widgets inside a panel
                 state.ui.begin_panel("Debug", 10.0, 10.0, 250.0, 400.0);
                 state.ui.text("Voltex Editor Demo");