perf: pause background polling and animations when tab is hidden

- Background polling pauses when tab is not visible
- Timer-based animations replaced with efficient frame-based updates
- Reduced CPU usage when OpenChamber is in background

packages/ui/src/components/desktop/DesktopHostSwitcher.tsx

@@ -405,6 +405,10 @@ export function DesktopHostSwitcherDialog({
     };
     void run();
     const interval = window.setInterval(() => {
+      // Skip polling when tab is hidden to reduce background work
+      if (typeof document !== 'undefined' && document.visibilityState !== 'visible') {
+        return;
+      }
       void run();
     }, 1_500);
 
@@ -1255,6 +1259,10 @@ export function DesktopHostSwitcherButton({ headerIconButtonClass }: DesktopHost
 
     void run();
     const interval = window.setInterval(() => {
+      // Skip polling when tab is hidden to reduce background work
+      if (typeof document !== 'undefined' && document.visibilityState !== 'visible') {
+        return;
+      }
       void run();
     }, 10_000);
     return () => {