Add asynchronous page content request

assets/page.erb

@@ -144,6 +144,19 @@
   <h1><span><%= hostname %></span> status - MALP</h1>
 </header>
 
+<% if authenticated %>
+  <div id="content"></div>
+  <script>
+    fetch("?content", { credentials: "same-origin" })
+      .then(function(response) {
+        if (response.ok) return response.text();
+      })
+      .then(function(html) {
+        if (html) document.getElementById("content").innerHTML = html;
+      });
+  </script>
+<% end %>
+
 <% unless authenticated %>
   <div class="card">
     <div class="card-title">Sign In</div>