refactor templates layout

@see https://gohugo.io/templates/new-templatesystem-overview/

layouts/_partials/single/main-header/item-tile.html

@@ -0,0 +1,67 @@
+{{- /*
+  Renders the header tile for an item.
+
+  @params pc  The page context.
+  @params sc  The site context.
+  */
+-}}
+
+{{- if ( not ( isset . "sc" ) ) -}}
+  {{- errorf "No site context received" -}}
+{{- end -}}
+
+{{- if ( not ( isset . "pc" ) ) -}}
+  {{- errorf "No page context received (%q)" .sc.Page.File.Dir -}}
+{{- end -}}
+
+{{ with .pc.Params.featured_image }}
+  <img
+    class="u-photo"
+    style="display: none;"
+    src="
+    {{- with ( $.pc.Resources.GetMatch . ) -}}
+      {{- partialCached "images/get-image.html" ( dict "img" . ) .Title -}}
+    {{- else -}}
+      {{- . -}}
+    {{- end -}}
+    "
+    itemprop="image"
+    {{- with ( $.pc.Resources.GetMatch . ) -}}
+      alt="{{ .Params.alt }}"
+    {{- end -}}
+  />
+{{ end }}
+
+
+<div
+  class="article-header__featured-image"
+  {{ with .pc.Params.featured_image }}
+    {{ with ( $.pc.Resources.GetMatch . ) }}
+      style="background-image: url({{- partialCached "images/get-image.html" ( dict "img" . ) .Title -}})"
+    {{ else }}
+      {{- if $.pc.Page.Resources -}}
+        {{- errorf "No Page Resource found for src '%q' (%q).\n\n\tAvailable Page Resources are:\n\t\t%v" . $.pc.Page.File.Path $.pc.Page.Resources -}}
+      {{- else -}}
+        {{- warnf "No Page Resource found for src '%q' (%q)." . $.pc.Page.File.Path -}}
+      {{- end -}}
+      style="background-image: url({{ . }})"
+    {{ end }}
+  {{ end -}}
+>
+  <div class="article-header__title-wrapper">
+    <a
+      class="u-url u-uid"
+      style="display: none"
+      href="{{ .pc.Permalink }}"
+    ></a>
+    {{- with .pc.File -}}
+      {{- partial "text/item-title.html" ( dict "pc" $.pc "sc" $.sc "class" "article-header" ) -}}
+    {{- else -}}
+      {{- partial "text/item-title.html" ( dict "pc" $.pc "sc" $.sc "class" "article-header" ) -}}
+    {{- end -}}
+  </div>
+
+  {{ with ( .pc.Resources.GetMatch .pc.Params.featured_image ) }}
+    {{- partial "media/attr.html" ( dict "pc" $.pc "sc" $.sc "params" .Params ) -}}
+  {{ end }}
+</div>