show author on articles (single page byline + journal listing)

- Single page: 'von {Author} · {Date}' byline directly under H1 in
  mono, editorial-style. Falls back to site.Params.author.name.
- Journal listing: author appended to existing meta row.
- Bottom .time line cleaned: only renders if there's reading time
  or a meaningful lastmod, to avoid an empty meta strip.

Per-page override via 'author' frontmatter field; until set,
everything is credited to the site default author.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

layouts/index.html

@@ -13,12 +13,14 @@
     <ol class="journal-list">
       {{ range $journal }}
         <li class="journal-entry">
+          {{ $author := .Params.author | default site.Params.author.name }}
           <a class="journal-entry-link" href="{{ .RelPermalink }}">
             <div class="journal-meta">
               {{ with .Parent }}
                 <span class="journal-section">{{ .Title }}</span>
               {{ end }}
               <time class="journal-date" datetime="{{ .Date.Format "2006-01-02" }}">{{ .Date.Format "2006-01-02" }}</time>
+              {{ with $author }}<span class="journal-author">{{ . }}</span>{{ end }}
             </div>
             <h3 class="journal-title">{{ .LinkTitle }}</h3>
             {{ with .Params.summary }}