refactor: use english for routes, parameters and internal messages

templates/booking/index.html.twig

@@ -57,7 +57,7 @@
                     </div>
                     <div class="flex items-center gap-3">
                         <a class="text-sm underline"
-                           href="{{ path('app_board', { type: booking.resource.type.slug, tag: booking.date|date('Y-m-d') }) }}">Im Plan</a>
+                           href="{{ path('app_board', { type: booking.resource.type.value, date: booking.date|date('Y-m-d') }) }}">Im Plan</a>
                         {# Ordinary form post: this page has no board fragments to swap, so it
                            reloads afterwards rather than pretending to be htmx. #}
                         <form method="post" action="{{ path('app_booking_release', { id: booking.id }) }}">