Add standalone backup script and admin update-check banner

ops/backup.sh snapshots LDAP (slapcat), Redis (BGSAVE, dynamic RDB path
lookup), and ./config for standalone deployments, with retention. A
background service polls GitHub releases every 24h and surfaces an
admin-only banner in the UI when a newer version is published.

nodejs/services/update_check.js

@@ -0,0 +1,26 @@
+'use strict';
+
+const conf = require('@simpleworkjs/conf');
+const updateCheck = require('../utils/update_check');
+
+function updateCheckService(){
+	/**
+	* Update Check Service
+	*
+	* Periodically asks GitHub for the latest published release of this repo
+	* and compares it to the running version (nodejs/package.json). Never
+	* auto-updates anything -- just makes the result available via
+	* GET /api/update-check (see routes/update_check.js) so the admin UI can
+	* show a banner when a newer release exists.
+	*/
+
+	setTimeout(updateCheck.checkNow, conf.service.updateCheck.initial);
+	setInterval(updateCheck.checkNow, conf.service.updateCheck.interval);
+
+	console.log('Update check service initialized');
+	console.log(`- Checking ${updateCheck.REPO} releases: 30s after start, then every 24h`);
+}
+
+if(conf.service.updateCheck.enabled !== false) updateCheckService();
+
+module.exports = {};