security: swap sanitizer to xss and harden logging

- Replace isomorphic-dompurify with xss to avoid ESM-only transitive
  dependencies (jsdom/htmlparser2) that break the existing Jest test suite.
- Sanitize rendered docs and Terms-of-Service HTML via xss() in routes/docs.js
  and routes/index.js.
- Remove full-object new-user logging from models/user_ldap.js and reduce
  login-path error output to error.name/error.message only.

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

nodejs/routes/docs.js

@@ -4,7 +4,7 @@ const fs = require('fs');
 const path = require('path');
 const router = require('express').Router();
 const {marked} = require('marked');
-const DOMPurify = require('isomorphic-dompurify');
+const xss = require('xss');
 const conf = require('@simpleworkjs/conf');
 const buildInfo = require('../utils/build_info');
 const rateLimit = require('../middleware/rate_limit');
@@ -132,7 +132,7 @@ router.get('/:slug', function(req, res, next) {
 			docs: docList,
 			currentSlug: req.params.slug,
 			docTitle: doc.title,
-			docHtml: DOMPurify.sanitize(fixDocLinks(fixImagePaths(marked(content)))),
+			docHtml: xss(fixDocLinks(fixImagePaths(marked(content)))),
 		});
 	} catch (error) {
 		next(error);