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/auth_provider.dart

@@ -63,13 +63,19 @@ class AuthProvider extends ChangeNotifier {
   Future<void> _initializeServices() async {
     try {
       await _pushService.initialize();
-    } catch (_) {}
+    } catch (e) {
+      debugPrint('AuthProvider: push service init error: $e');
+    }
     try {
       await _voiceService.initialize();
-    } catch (_) {}
+    } catch (e) {
+      debugPrint('AuthProvider: voice service init error: $e');
+    }
     try {
       await _sseService.connect();
-    } catch (_) {}
+    } catch (e) {
+      debugPrint('AuthProvider: SSE connect error: $e');
+    }
   }
 
   Future<void> logout() async {