Fix mobile app: AccessToken for voice, Agent Manager for status, caller ID support

- Voice token: use AccessToken + VoiceGrant instead of browser-only ClientToken
- Agent status: delegate to TWP_Agent_Manager matching browser phone behavior
- Queue loading: add missing require_once for TWP_User_Queue_Manager
- Add /phone-numbers endpoint for caller ID selection
- Webhook: support CallerId param from mobile extraOptions
- Flutter: caller ID dropdown in dialer, error logging in all catch blocks

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

mobile/lib/providers/agent_provider.dart

@@ -5,6 +5,16 @@ import '../models/queue_state.dart';
 import '../services/api_client.dart';
 import '../services/sse_service.dart';
 
+class PhoneNumber {
+  final String phoneNumber;
+  final String friendlyName;
+  PhoneNumber({required this.phoneNumber, required this.friendlyName});
+  factory PhoneNumber.fromJson(Map<String, dynamic> json) => PhoneNumber(
+    phoneNumber: json['phone_number'] as String,
+    friendlyName: json['friendly_name'] as String,
+  );
+}
+
 class AgentProvider extends ChangeNotifier {
   final ApiClient _api;
   final SseService _sse;
@@ -12,12 +22,14 @@ class AgentProvider extends ChangeNotifier {
   AgentStatus? _status;
   List<QueueInfo> _queues = [];
   bool _sseConnected = false;
+  List<PhoneNumber> _phoneNumbers = [];
   StreamSubscription? _sseSub;
   StreamSubscription? _connSub;
 
   AgentStatus? get status => _status;
   List<QueueInfo> get queues => _queues;
   bool get sseConnected => _sseConnected;
+  List<PhoneNumber> get phoneNumbers => _phoneNumbers;
 
   AgentProvider(this._api, this._sse) {
     _connSub = _sse.connectionState.listen((connected) {
@@ -33,7 +45,7 @@ class AgentProvider extends ChangeNotifier {
       final response = await _api.dio.get('/agent/status');
       _status = AgentStatus.fromJson(response.data);
       notifyListeners();
-    } catch (_) {}
+    } catch (e) { debugPrint('AgentProvider.fetchStatus error: $e'); }
   }
 
   Future<void> updateStatus(AgentStatusValue newStatus) async {
@@ -49,7 +61,7 @@ class AgentProvider extends ChangeNotifier {
         currentCallSid: _status?.currentCallSid,
       );
       notifyListeners();
-    } catch (_) {}
+    } catch (e) { debugPrint('AgentProvider.updateStatus error: $e'); }
   }
 
   Future<void> fetchQueues() async {
@@ -60,11 +72,24 @@ class AgentProvider extends ChangeNotifier {
           .map((q) => QueueInfo.fromJson(q as Map<String, dynamic>))
           .toList();
       notifyListeners();
-    } catch (_) {}
+    } catch (e) { debugPrint('AgentProvider.fetchQueues error: $e'); }
+  }
+
+  Future<void> fetchPhoneNumbers() async {
+    try {
+      final response = await _api.dio.get('/phone-numbers');
+      final data = response.data;
+      _phoneNumbers = (data['phone_numbers'] as List)
+          .map((p) => PhoneNumber.fromJson(p as Map<String, dynamic>))
+          .toList();
+      notifyListeners();
+    } catch (e) {
+      debugPrint('AgentProvider.fetchPhoneNumbers error: $e');
+    }
   }
 
   Future<void> refresh() async {
-    await Future.wait([fetchStatus(), fetchQueues()]);
+    await Future.wait([fetchStatus(), fetchQueues(), fetchPhoneNumbers()]);
   }
 
   void _handleSseEvent(SseEvent event) {