feat(CallFeature): implement call functionality and integrate WebSocket signaling

- Updated app.json to include microphone permissions and background audio support.
- Added call-related dependencies in package.json and package-lock.json.
- Enhanced ChatScreen to initiate calls and handle call actions.
- Introduced call components in the layout for incoming call handling.
- Expanded WebSocket service to manage call signaling messages and events.
- Refactored authStore to initialize call state on user authentication.

src/components/call/index.ts

@@ -0,0 +1,3 @@
+export { default as CallScreen } from './CallScreen';
+export { default as IncomingCallModal } from './IncomingCallModal';
+export { default as FloatingCallWindow } from './FloatingCallWindow';