chat client: re-add livereload

public/assets/chat/znuny.html

@@ -5,6 +5,7 @@
   <title>Zammad Chat</title>
   <link rel="stylesheet" href="znuny.css">
   <meta name="viewport" content="width=device-width,initial-scale=1.0">
+  <script>document.write('<script src="http://' + (location.host || 'localhost').split(':')[0] + ':35729/livereload.js?snipver=1"></' + 'script>')</script>
   <style>
     body {
       margin: 0;