several fixes and optimizations

layouts/_default/begabtenfoerderung.html

@@ -1,5 +1,9 @@
 <div class="card border-primary rounded-0 hover-shadow mb-5">
+  {{ if .Params.Image }}
   <img class="card-img-top rounded-0" src="{{ .Params.Image | relURL }}" alt="{{ .Title }}">
+  {{ else }}
+  <img class="card-img-top rounded-0" src="/media/begabtenfoerderung/image.png" alt="{{ .Title }}">
+  {{ end }}
   <div class="card-body">
     <ul class="list-inline">
       <li class="list-inline-item"><p><i class="fa-solid fa-book-bookmark"></i> {{ .Params.Category }}</p></li>