refactor: added SPDX license information

Author: mfranzke

xo.config.mjs

@@ -1,4 +1,9 @@
+// SPDX-FileCopyrightText: 2025 DB Systel GmbH
+//
+// SPDX-License-Identifier: Apache-2.0
 /** @type {import('xo').FlatXoConfig} */
-const xoConfig = [{ ignores: ['**/build', '**/public', '**/out'] }];
+const xoConfig = [
+	{ ignores: ['**/build', '**/public', '**/out'], prettier: true }
+];
 
 export default xoConfig;