Replace native Twilio Voice SDK with WebView-based softphone

Rewrites the mobile app from a native Twilio Voice SDK integration
(Android Telecom/ConnectionService) to a thin WebView shell that loads
a standalone browser phone page from WordPress. This eliminates the
buggy Android phone account registration, fixes frequent logouts by
using 7-day WP session cookies instead of JWT tokens, and maintains
all existing call features (dialpad, queues, hold, transfer, requeue,
recording, caller ID, agent status).

Server-side:
- Add class-twp-mobile-phone-page.php: standalone /twp-phone/ endpoint
  with mobile-optimized UI, dark mode, tab navigation, and Flutter
  WebView JS bridge
- Extend auth cookie to 7 days for phone agents
- Add WP AJAX handler for FCM token registration (cookie auth)

Flutter app (v2.0.0):
- Replace 18 native files with 5-file WebView shell
- Login via wp-login.php in WebView (auto-detect redirect on success)
- Full-screen WebView with auto microphone grant for WebRTC
- FCM push notifications preserved for queue alerts
- Remove: twilio_voice, dio, provider, JWT auth, SSE, native call UI

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

mobile/lib/services/push_notification_service.dart

@@ -3,12 +3,11 @@ import 'package:firebase_core/firebase_core.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
-import 'api_client.dart';
 
 /// Notification ID for queue alerts (fixed so we can cancel it).
 const int _queueAlertNotificationId = 9001;
 
-/// Background handler — must be top-level function.
+/// Background handler -- must be top-level function.
 @pragma('vm:entry-point')
 Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
   await Firebase.initializeApp();
@@ -21,7 +20,6 @@ Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
     final plugin = FlutterLocalNotificationsPlugin();
     await plugin.cancel(_queueAlertNotificationId);
   }
-  // VoIP pushes handled natively by twilio_voice plugin.
 }
 
 /// Show an insistent queue alert notification (works from background handler too).
@@ -57,8 +55,12 @@ Future<void> _showQueueAlertNotification(Map<String, dynamic> data) async {
   );
 }
 
+/// Push notification service for queue alerts and general notifications.
+///
+/// FCM token registration is handled via the WebView JavaScript bridge
+/// instead of a REST API call. The token is exposed via [fcmToken] and
+/// injected into the web page by [PhoneScreen].
 class PushNotificationService {
-  final ApiClient _api;
   final FirebaseMessaging _messaging = FirebaseMessaging.instance;
   final FlutterLocalNotificationsPlugin _localNotifications =
       FlutterLocalNotificationsPlugin();
@@ -66,8 +68,6 @@ class PushNotificationService {
 
   String? get fcmToken => _fcmToken;
 
-  PushNotificationService(this._api);
-
   Future<void> initialize() async {
     FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);
 
@@ -84,43 +84,37 @@ class PushNotificationService {
     const initSettings = InitializationSettings(android: androidSettings);
     await _localNotifications.initialize(initSettings);
 
-    // Get and register FCM token
+    // Get FCM token
     final token = await _messaging.getToken();
-    debugPrint('FCM token: ${token != null ? "${token.substring(0, 20)}..." : "NULL"}');
+    debugPrint(
+        'FCM token: ${token != null ? "${token.substring(0, 20)}..." : "NULL"}');
     if (token != null) {
       _fcmToken = token;
-      await _registerToken(token);
     } else {
-      debugPrint('FCM: Failed to get token - Firebase may not be configured correctly');
+      debugPrint(
+          'FCM: Failed to get token - Firebase may not be configured correctly');
     }
 
     // Listen for token refresh
-    _messaging.onTokenRefresh.listen(_registerToken);
+    _messaging.onTokenRefresh.listen((token) {
+      _fcmToken = token;
+    });
 
-    // Handle foreground messages (non-VoIP)
+    // Handle foreground messages
     FirebaseMessaging.onMessage.listen(_handleForegroundMessage);
   }
 
-  Future<void> _registerToken(String token) async {
-    try {
-      await _api.dio.post('/fcm/register', data: {'fcm_token': token});
-    } catch (_) {}
-  }
-
   void _handleForegroundMessage(RemoteMessage message) {
     final data = message.data;
     final type = data['type'];
 
-    // VoIP incoming_call is handled by twilio_voice natively
-    if (type == 'incoming_call') return;
-
-    // Queue alert — show insistent notification
+    // Queue alert -- show insistent notification
     if (type == 'queue_alert') {
       _showQueueAlertNotification(data);
       return;
     }
 
-    // Queue alert cancel — dismiss notification
+    // Queue alert cancel -- dismiss notification
     if (type == 'queue_alert_cancel') {
       _localNotifications.cancel(_queueAlertNotificationId);
       return;
@@ -142,7 +136,7 @@ class PushNotificationService {
     );
   }
 
-  /// Cancel any active queue alert (called when agent accepts a call in-app).
+  /// Cancel any active queue alert.
   void cancelQueueAlert() {
     _localNotifications.cancel(_queueAlertNotificationId);
   }