Add logging for generated registration authentication code in server_service

lib/services/server_service.dart

@@ -21,6 +21,7 @@ class ServerService {
     
     // Generate registration rolling code
     String registrationAuth = RollingCodesService.generateRegistrationCode();
+    print('Generated registration auth: $registrationAuth');
     
     // Call server-manager registration endpoint
     String serverManagerUrl = 'https://lsdrctuvnwdrzrdyoqzu.supabase.co/functions/v1/server-manager/register';