ui: speed up page load

packages/recaptcha/frontend/captcha-main.page.js

@@ -0,0 +1,16 @@
+import { addPage, NamedPage } from '@hydrooj/ui-default';
+/* global grecaptcha */
+
+addPage(new NamedPage('user_register', () => {
+  function captcha(event) {
+    event.preventDefault();
+    grecaptcha.ready(() => {
+      grecaptcha.execute(UiContext.recaptchaKey, { action: 'submit' }).then((token) => {
+        document.getElementById('_captcha').value = token;
+        document.getElementById('_submit').click();
+      });
+    });
+  }
+  const element = document.getElementById('submit');
+  if (element) element.onclick = captcha;
+}));