chore: higher resolution voucher thumbnails, drop source pdfs

templates/voucher/index.html.twig

@@ -1,12 +0,0 @@
-{% extends 'layout_booking.html.twig' %}
-
-{% block title %}Gutschein kaufen{% endblock %}
-
-{% block content %}
-    <div class="flex-1 flex items-center justify-center"
-         hx-post="{{ path('app_voucher_init', { r: returnUrl }) }}"
-         hx-trigger="load"
-         hx-swap="none">
-        {% include '_partials/_spinner.html.twig' %}
-    </div>
-{% endblock %}