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/services/voice_service.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'package:flutter/foundation.dart';
 import 'package:twilio_voice/twilio_voice.dart';
 import 'api_client.dart';
 
@@ -36,7 +37,7 @@ class VoiceService {
       _identity = data['identity'] as String;
       await TwilioVoice.instance.setTokens(accessToken: token);
     } catch (e) {
-      // Token fetch failed - will retry on next interval
+      debugPrint('VoiceService._fetchAndRegisterToken error: $e');
     }
   }
 
@@ -62,8 +63,21 @@ class VoiceService {
     await TwilioVoice.instance.call.toggleSpeaker(speaker);
   }
 
-  Future<bool> makeCall(String to) async {
-    return await TwilioVoice.instance.call.place(to: to, from: _identity ?? '') ?? false;
+  Future<bool> makeCall(String to, {String? callerId}) async {
+    try {
+      final extraOptions = <String, dynamic>{};
+      if (callerId != null && callerId.isNotEmpty) {
+        extraOptions['CallerId'] = callerId;
+      }
+      return await TwilioVoice.instance.call.place(
+        to: to,
+        from: _identity ?? '',
+        extraOptions: extraOptions,
+      ) ?? false;
+    } catch (e) {
+      debugPrint('VoiceService.makeCall error: $e');
+      return false;
+    }
   }
 
   Future<void> sendDigits(String digits) async {