Autor-Seiten: /authors/<slug>/ (rundes Bild, Name, Bio, zentriert) + Byline-Link

- layouts/authors/single.html rendert die Autor-Seite zentriert
- Byline in single.html + index.html verlinkt den Autornamen zu /authors/<urlize name>/
  (nur wenn die Seite existiert)
- CMS-Profil-Speichern schreibt content/authors/<slug>.md (aus Name/Bio/Avatar)
  + data/authors.json und baut public neu → Seite & Links sofort live
- Autor-Seiten aus dem Inhalts-Editor ausgeblendet (über „Profil" verwaltet)
- custom.css: .author-page / -photo / -name / -bio + Byline-Link-Stil

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

layouts/_default/single.html

@@ -16,9 +16,13 @@
         <p class="single-summary">{{ . }}</p>
       {{ end }}
       {{ $author := .Params.author | default site.Params.author.name }}
+      {{ $authorPage := cond (ne $author "") (site.GetPage (printf "/authors/%s" (urlize $author))) false }}
       {{ if or $author .Date }}
         <p class="single-byline">
-          {{- with $author -}}<span class="byline-author">{{ . }}</span>{{- end -}}
+          {{- with $author -}}
+            {{- if $authorPage -}}<a class="byline-author" href="{{ $authorPage.RelPermalink }}">{{ . }}</a>
+            {{- else -}}<span class="byline-author">{{ . }}</span>{{- end -}}
+          {{- end -}}
           {{- if and $author .Date -}}, {{ end -}}
           {{- if .Date -}}<time class="byline-date" datetime="{{ .Date.Format "2006-01-02" }}">{{ .Date.Format "02.01.2006" }}</time>{{- end -}}
         </p>