Fix code scanning alert #455: Incomplete string escaping or encoding

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

server-data/resources/[bpt_addons]/bpt_idcard/html/assets/js/materialize.js

@@ -1244,7 +1244,7 @@ M.guid = function () {
  * @returns {string}
  */
 M.escapeHash = function (hash) {
-    return hash.replace(/(:|\.|\[|\]|,|=|\/)/g, "\\$1");
+    return hash.replace(/\\/g, "\\\\").replace(/(:|\.|\[|\]|,|=|\/)/g, "\\$1");
 };
 
 M.elementOrParentIsFixed = function (element) {