add ticket purchase page

Co-authored-by: Jan-Marlon Leibl <jleibl@proton.me>
Reviewed-on: http://git.simonis.lol/projects/abiball/pulls/13
Reviewed-by: jank1619 <jan@kjan.email>

assets/app.js

@@ -1,9 +1,2 @@
-/*
- * Welcome to your app's main JavaScript file!
- *
- * This file will be included onto the page via the importmap() Twig function,
- * which should already be in your base.html.twig.
- */
-import './styles/app.css';
-
-console.log('This log comes from assets/app.js - welcome to AssetMapper! 🎉');
+import "./bootstrap.js";
+import "./styles/app.css";