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/providers/call_provider.dart

@@ -10,6 +10,7 @@ class CallProvider extends ChangeNotifier {
   Timer? _durationTimer;
   StreamSubscription? _eventSub;
   DateTime? _connectedAt;
+  bool _pendingAutoAnswer = false;
 
   CallInfo get callInfo => _callInfo;
 
@@ -20,9 +21,13 @@ class CallProvider extends ChangeNotifier {
   void _handleCallEvent(CallEvent event) {
     switch (event) {
       case CallEvent.incoming:
-        _callInfo = _callInfo.copyWith(
-          state: CallState.ringing,
-        );
+        if (_pendingAutoAnswer) {
+          _pendingAutoAnswer = false;
+          _callInfo = _callInfo.copyWith(state: CallState.connecting);
+          _voiceService.answer();
+        } else {
+          _callInfo = _callInfo.copyWith(state: CallState.ringing);
+        }
         break;
       case CallEvent.ringing:
         _callInfo = _callInfo.copyWith(state: CallState.connecting);
@@ -47,20 +52,24 @@ class CallProvider extends ChangeNotifier {
         break;
     }
 
-    // Update caller info from active call
-    final call = TwilioVoice.instance.call;
-    final active = call.activeCall;
-    if (active != null) {
-      _callInfo = _callInfo.copyWith(
-        callerNumber: active.from,
-      );
-      // Fetch SID asynchronously
-      call.getSid().then((sid) {
-        if (sid != null && sid != _callInfo.callSid) {
-          _callInfo = _callInfo.copyWith(callSid: sid);
-          notifyListeners();
+    // Update caller info from active call (skip if call just ended)
+    if (_callInfo.state != CallState.idle) {
+      final call = TwilioVoice.instance.call;
+      final active = call.activeCall;
+      if (active != null) {
+        if (_callInfo.callerNumber == null) {
+          _callInfo = _callInfo.copyWith(
+            callerNumber: active.from,
+          );
         }
-      });
+        // Fetch SID asynchronously
+        call.getSid().then((sid) {
+          if (sid != null && sid != _callInfo.callSid && _callInfo.isActive) {
+            _callInfo = _callInfo.copyWith(callSid: sid);
+            notifyListeners();
+          }
+        });
+      }
     }
 
     notifyListeners();
@@ -85,7 +94,16 @@ class CallProvider extends ChangeNotifier {
 
   Future<void> answer() => _voiceService.answer();
   Future<void> reject() => _voiceService.reject();
-  Future<void> hangUp() => _voiceService.hangUp();
+  Future<void> hangUp() async {
+    await _voiceService.hangUp();
+    // If SDK didn't fire callEnded (e.g. no active SDK call), reset manually
+    if (_callInfo.state != CallState.idle) {
+      _stopDurationTimer();
+      _callInfo = const CallInfo();
+      _pendingAutoAnswer = false;
+      notifyListeners();
+    }
+  }
 
   Future<void> toggleMute() async {
     final newMuted = !_callInfo.isMuted;
@@ -109,7 +127,12 @@ class CallProvider extends ChangeNotifier {
       callerNumber: number,
     );
     notifyListeners();
-    await _voiceService.makeCall(number, callerId: callerId);
+    final success = await _voiceService.makeCall(number, callerId: callerId);
+    if (!success) {
+      debugPrint('CallProvider.makeCall: call.place() returned false');
+      _callInfo = const CallInfo(); // reset to idle
+      notifyListeners();
+    }
   }
 
   Future<void> holdCall() async {
@@ -134,6 +157,20 @@ class CallProvider extends ChangeNotifier {
     await _voiceService.transferCall(sid, target);
   }
 
+  Future<void> acceptQueueCall(String callSid) async {
+    _pendingAutoAnswer = true;
+    _callInfo = _callInfo.copyWith(state: CallState.connecting);
+    notifyListeners();
+    try {
+      await _voiceService.acceptQueueCall(callSid);
+    } catch (e) {
+      debugPrint('CallProvider.acceptQueueCall error: $e');
+      _pendingAutoAnswer = false;
+      _callInfo = const CallInfo();
+      notifyListeners();
+    }
+  }
+
   @override
   void dispose() {
     _stopDurationTimer();