Add crossorigin attribute to script to work around Safari issue

See: https://stackoverflow.com/a/56755581

src/web/control.ejs

@@ -14,6 +14,7 @@
       type="module"
       id="main-script"
       data-ws-endpoint="<%= wsEndpoint %>"
+      crossorigin
     ></script>
   </body>
 </html>