Add FCM push notifications, queue alerts, caller ID fixes, and auto-revert agent status

Server-side:
- Add push credential auto-creation for FCM incoming call notifications
- Add queue alert FCM notifications (data-only for background delivery)
- Add queue alert cancellation on call accept/disconnect
- Fix caller ID to show caller's number instead of Twilio number
- Fix FCM token storage when refresh_token is null
- Add pre_call_status tracking to revert agent status 30s after call ends
- Add SSE fallback polling for mobile app connectivity

Mobile app:
- Add Android telecom permissions and phone account registration
- Add VoiceFirebaseMessagingService for incoming call push handling
- Add insistent queue alert notifications with custom sound
- Fix caller number display on active call screen
- Add caller ID selection dropdown on dashboard
- Add phone numbers endpoint and provider support
- Add unit tests for CallInfo, QueueState, and CallProvider
- Remove local.properties from tracking, add .gitignore

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

mobile/lib/services/push_notification_service.dart

@@ -1,13 +1,60 @@
+import 'dart:typed_data';
 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.
 @pragma('vm:entry-point')
 Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
   await Firebase.initializeApp();
-  // VoIP pushes are handled natively by twilio_voice plugin.
-  // Other data messages can show a local notification if needed.
+  final data = message.data;
+  final type = data['type'];
+
+  if (type == 'queue_alert') {
+    await _showQueueAlertNotification(data);
+  } else if (type == 'queue_alert_cancel') {
+    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).
+Future<void> _showQueueAlertNotification(Map<String, dynamic> data) async {
+  final plugin = FlutterLocalNotificationsPlugin();
+
+  final title = data['title'] ?? 'Call Waiting';
+  final body = data['body'] ?? 'New call in queue';
+
+  final androidDetails = AndroidNotificationDetails(
+    'twp_queue_alerts',
+    'Queue Alerts',
+    channelDescription: 'Alerts when calls are waiting in queue',
+    importance: Importance.max,
+    priority: Priority.max,
+    playSound: true,
+    sound: const RawResourceAndroidNotificationSound('queue_alert'),
+    enableVibration: true,
+    vibrationPattern: Int64List.fromList([0, 500, 200, 500, 200, 500]),
+    ongoing: true,
+    autoCancel: false,
+    category: AndroidNotificationCategory.alarm,
+    additionalFlags: Int32List.fromList([4]), // FLAG_INSISTENT = 4
+    fullScreenIntent: true,
+    visibility: NotificationVisibility.public,
+  );
+
+  await plugin.show(
+    _queueAlertNotificationId,
+    title,
+    body,
+    NotificationDetails(android: androidDetails),
+  );
 }
 
 class PushNotificationService {
@@ -15,6 +62,9 @@ class PushNotificationService {
   final FirebaseMessaging _messaging = FirebaseMessaging.instance;
   final FlutterLocalNotificationsPlugin _localNotifications =
       FlutterLocalNotificationsPlugin();
+  String? _fcmToken;
+
+  String? get fcmToken => _fcmToken;
 
   PushNotificationService(this._api);
 
@@ -36,8 +86,12 @@ class PushNotificationService {
 
     // Get and register FCM token
     final token = await _messaging.getToken();
+    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');
     }
 
     // Listen for token refresh
@@ -60,7 +114,19 @@ class PushNotificationService {
     // VoIP incoming_call is handled by twilio_voice natively
     if (type == 'incoming_call') return;
 
-    // Show local notification for other types (missed call, queue alert, etc.)
+    // Queue alert — show insistent notification
+    if (type == 'queue_alert') {
+      _showQueueAlertNotification(data);
+      return;
+    }
+
+    // Queue alert cancel — dismiss notification
+    if (type == 'queue_alert_cancel') {
+      _localNotifications.cancel(_queueAlertNotificationId);
+      return;
+    }
+
+    // Show local notification for other types (missed call, etc.)
     _localNotifications.show(
       message.hashCode,
       data['title'] ?? 'TWP Softphone',
@@ -75,4 +141,9 @@ class PushNotificationService {
       ),
     );
   }
+
+  /// Cancel any active queue alert (called when agent accepts a call in-app).
+  void cancelQueueAlert() {
+    _localNotifications.cancel(_queueAlertNotificationId);
+  }
 }