feat(call): migrate from WebRTC to LiveKit

Replace the custom WebRTC implementation with LiveKit for improved
stability and feature support.

- Remove `react-native-webrtc` and custom `WebRTCManager`
- Implement `LiveKitService` for room and track management
- Update `callStore` to handle LiveKit events and connection states
- Refactor `CallScreen` (mobile and web) to use `@livekit/react-native`
  and `VideoView`
- Update WebSocket protocol to use `call_ready` instead of manual SDP/ICE
  exchanges
- Add necessary camera and microphone permissions to `app.json`
- Update Metro and Babel configurations for LiveKit compatibility

metro.config.js

@@ -7,8 +7,7 @@ const config = getDefaultConfig(__dirname);
 // Add wasm asset support
 config.resolver.assetExts.push('wasm');
 
-// Fix for react-native-webrtc event-target-shim import warning
-// The package doesn't properly export "./index" in its exports field
+// Fix for livekit-client event-target-shim import warning
 config.resolver.unstable_enablePackageExports = false;
 
 // Support TypeScript path aliases (@/ -> ./src/)
@@ -36,7 +35,6 @@ const webShimPaths = [
 // These packages import requireNativeComponent directly from 'react-native'
 // (which resolves to react-native-web on web) and don't have web implementations.
 const webPackageShims = {
-  'react-native-webrtc': path.resolve(__dirname, 'web-shims/react-native-webrtc/index.js'),
 };
 
 const originalResolveRequest = config.resolver.resolveRequest;