fix(ribbon): highlight toggle buttons by their actual state

The UCS Icon, Properties, File Tabs, and Layout Tabs buttons were highlighted unconditionally because their ids fell through to an active_tool equality check in is_active_tool, which activate_tool sets on every click and never clears. Each id is now mapped to its corresponding visibility flag (show_ucs_icon, show_properties, show_file_tabs, show_layout_tabs), and those flags are kept in sync from their toggle handlers so the highlight reflects live state. The per-toggle booleans previously threaded through the render path are consolidated into a single ToggleState struct read from one place, so introducing a further toggle no longer requires changing every render-function signature and call site.

src/app/commands/display.rs

@@ -81,6 +81,7 @@ impl OpenCADStudio {
                         let at_origin = sub == "ORIGIN";
                         // Update model-space icon flags.
                         self.show_ucs_icon = visible;
+                        self.ribbon.set_ucs_icon(visible);
                         if sub == "NOORIGIN" || sub == "ORIGIN" {
                             self.ucs_icon_at_origin = at_origin;
                         }
@@ -104,6 +105,7 @@ impl OpenCADStudio {
                         self.push_undo_snapshot(i, "UCSICON");
                         let visible = !self.show_ucs_icon;
                         self.show_ucs_icon = visible;
+                        self.ribbon.set_ucs_icon(visible);
                         for entity in self.tabs[i].scene.document.entities_mut() {
                             if let acadrust::EntityType::Viewport(vp) = entity {
                                 vp.status.ucs_icon_visible = visible;