feat(livekit): improve native audio/video handling and stability

Implement robust WebRTC polyfills and native audio session management for
LiveKit on mobile platforms. This includes configuring iOS audio sessions
to prevent issues during calls and implementing a delayed video
activation strategy to avoid main thread deadlocks on iOS.

- Add WebRTC and environment polyfills in `src/polyfills.ts`
- Implement iOS-specific `AudioSession` configuration in `LiveKitService`
- Add support for toggling speaker output on iOS
- Update `callStore` to handle video enablement after connection settles
- Fix `useUnreadCountQuery` to correctly handle async fetching

src/polyfills.ts

@@ -1,3 +1,38 @@
+import { Platform } from 'react-native';
+
+// Register WebRTC globals for LiveKit (native only — web has built-in WebRTC)
+if (Platform.OS !== 'web') {
+  // Use @livekit/react-native's registerGlobals which sets up:
+  // - WebRTC native modules (via @livekit/react-native-webrtc)
+  // - iOS audio session management
+  // - LiveKitReactNativeGlobal (so livekit-client detects RN environment)
+  // - RN-specific polyfills (Promise.allSettled, webstreams, crypto, etc.)
+  const { registerGlobals } = require('@livekit/react-native');
+  registerGlobals();
+}
+
+if (typeof globalThis.Event === 'undefined') {
+  (globalThis as any).Event = class Event {
+    type: string;
+    bubbles: boolean;
+    cancelable: boolean;
+    defaultPrevented: boolean;
+    target: any;
+    currentTarget: any;
+    constructor(type: string, opts?: { bubbles?: boolean; cancelable?: boolean }) {
+      this.type = type;
+      this.bubbles = opts?.bubbles ?? false;
+      this.cancelable = opts?.cancelable ?? false;
+      this.defaultPrevented = false;
+      this.target = null;
+      this.currentTarget = null;
+    }
+    preventDefault() { this.defaultPrevented = true; }
+    stopPropagation() {}
+    stopImmediatePropagation() {}
+  };
+}
+
 if (typeof globalThis.DOMException === 'undefined') {
   (globalThis as any).DOMException = class DOMException extends Error {
     constructor(message?: string, name?: string) {
@@ -5,4 +40,4 @@ if (typeof globalThis.DOMException === 'undefined') {
       this.name = name || 'DOMException';
     }
   };
-}
+}