feat: support leaf bundles for blog posts, refactor header images

themes/hugo-sustain/layouts/_default/single.html

@@ -40,12 +40,7 @@
         <div class="panel panel-default">
           <div class="panel-body">
             <div class="blogpost">
-              {{ if isset .Params "headerimage" }}
-                <div class="header-image">
-                  <img src="/img/{{ .Params.headerImage }}" />
-                  <p>{{ with .Params.headercredits }}{{ . | markdownify }}{{ end }}</p>
-                </div>
-              {{ end }}
+              {{ partial "blog/headerimage" . }}
               {{ .Content }}
               <!-- only show related posts if param is true, or if it's not a page -->
               {{ if or (eq .Params.related true) (ne .Params.page true) }}
@@ -85,6 +80,6 @@
 
     <!-- Matomo -->
     {{ partial "matomo" . }}
-    
+
   </body>
 </html>