refactor: Phase 2 - add error handling modules and response helpers

dashcaddy-api/server.js

@@ -60,6 +60,7 @@ const auditLogger = require('./audit-logger');
 const portLockManager = require('./port-lock-manager');
 const dockerSecurity = require('./docker-security');
 const authManager = require('./auth-manager');
+const responseHelpers = require('./response-helpers');
 const configureMiddleware = require('./middleware');
 const { validateStartupConfig, syncHealthCheckerServices } = require('./startup-validator');
 const { CSRF_HEADER_NAME } = require('./csrf-protection');
@@ -1960,3 +1961,4 @@ process.on('uncaughtException', (error) => {
   setTimeout(() => process.exit(1), 1000).unref();
 });
 
+