fix: enable web runtime notifications without push (#1322)

Web notifications now listen to the notification stream directly
Native notifications no longer depend on PWA push being enabled
Window focus is respected when deciding whether to send background push notifications

packages/ui/src/hooks/usePushVisibilityBeacon.ts

@@ -6,8 +6,7 @@ const HEARTBEAT_MS = 20000;
 
 const resolveVisibilityState = (): 'visible' | 'hidden' => {
   if (typeof document === 'undefined') return 'visible';
-  const state = document.visibilityState;
-  return state === 'hidden' && document.hasFocus() ? 'visible' : state;
+  return document.visibilityState === 'visible' && document.hasFocus() ? 'visible' : 'hidden';
 };
 
 const sendVisibility = (visible: boolean) => {