Add draft extensions loader

public/index.html

@@ -4936,5 +4936,6 @@
             </form>
         </div>
     </div>
+<script src="scripts/extensions.js"></script>
 </body>
 </html>

public/scripts/extensions.js

@@ -0,0 +1,21 @@
+const settings_html = `
+<hr>
+<div id="extensions_block">
+    <h3>Extensions</h3>
+    <input id="extensions_url" type="text" class="text_pole" />
+    <input id="extensions_connect" type="submit" value="Connect" />
+</div>
+`
+const urlKey = 'extensions_url';
+const defaultUrl = "http://localhost:5100";
+
+$(document).ready(async function() {
+    const url = localStorage.getItem(urlKey) ?? defaultUrl;
+    $('#rm_api_block').append(settings_html);
+    $("#extensions_url").val(url);
+    $("#extensions_connect").on('click', function() {
+        const url = $("#extensions_url").val();
+        localStorage.setItem(urlKey, url);
+        alert('click!');
+    });
+});