chore: relocate backend into apps/api ahead of monorepo merge

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/api/utils/response.util.js

@@ -0,0 +1,28 @@
+/***********************************************************************************************************************************************************************
+ * File Name: response.util.js
+ * Type of Program: Utility
+ * Description: Standardised HTTP response helpers.
+ *              Wraps all responses in a consistent envelope:
+ *              { status, message, data?, errors? }
+ * Author: rgrgogu
+ * Date Created: Oct. 6, 2025
+ ***********************************************************************************************************************************************************************
+ * HOW TO USE:
+ *   const R = require('../utils/response.util');
+ *   return R.success(res, 'User created', user, 201);
+ *   return R.error(res, 'Not found', 404);
+ ***********************************************************************************************************************************************************************/
+
+const success = (res, message = 'OK', data = null, statusCode = 200) =>
+  res.status(statusCode).json({ status: 'success', message, data });
+
+const error = (res, message = 'An error occurred', statusCode = 500, errors = null) => {
+  const body = { status: 'error', message };
+  if (errors) body.errors = errors;
+  return res.status(statusCode).json(body);
+};
+
+const validationError = (res, errors) =>
+  res.status(422).json({ status: 'error', message: 'Validation failed', errors });
+
+module.exports = { success, error, validationError };