custom JS removed in favor of proper CSRF implementation

assets/views/shop/show.html

@@ -63,6 +63,7 @@
     {% if product.stock > 0 %}
     <form method="post" action="/cart/add" hx-post="/cart/add" hx-swap="none" class="flex flex-wrap items-end gap-3"
       hx-on::after-request="if (event.detail.successful) toast('{{ t(key='cart-added', lang=lang | default(value='sk')) }}')">
+  {{ ui::csrf_field() }}
       <input type="hidden" name="product_id" value="{{ product.id }}">
       <div class="space-y-1.5">
         <label for="quantity" class="text-sm font-medium text-on-surface-strong dark:text-on-surface-dark-strong">{{ t(key="quantity", lang=lang | default(value='sk')) }}</label>