feat(authors): show author avatar in single-page byline

Replace the generic fa-user icon next to the byline with the author's
avatar, resolving the byline to its taxonomy term page and reusing the
author-avatar partial (avatar -> gravatar -> identicon fallback), so
un-enriched authors still get a sensible image.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: HeyItsGilbert

themes/powershell-community/layouts/_default/single.html

@@ -46,10 +46,9 @@ <h1 class="text-3xl lg:text-4xl font-bold text-gray-900 mb-4 leading-tight">{{ .
             <div class="flex items-center justify-between">
                 <div class="flex items-center space-x-4">
                     {{ with .Params.author }}
+                    {{ $authorPage := site.GetPage (printf "/authors/%s" (. | urlize)) }}
                     <div class="flex items-center text-gray-600">
-                        <div class="w-8 h-8 bg-blue-600 rounded-full flex items-center justify-center mr-3">
-                            <i class="fas fa-user text-white text-sm"></i>
-                        </div>
+                        {{ partial "author-avatar.html" (dict "page" $authorPage "name" . "size" 64 "class" "w-8 h-8 rounded-full object-cover mr-3") }}
                         <a href="{{ "/authors/" | relURL }}{{ . | urlize }}/" class="font-medium hover:text-blue-600 transition-colors duration-200">{{ . }}</a>
                     </div>
                     {{ end }}