Improve SEO with meta tags and structured data fixes

- Add og:image:width and og:image:height for better social previews
- Add twitter:image:alt for accessibility
- Add DNS prefetch for Google Analytics
- Add noindex to 404 page
- Fix schema.org context to use https://
- Add image dimensions to JSON-LD structured data

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: johanrin

layouts/partials/custom-head.html

@@ -1,11 +1,28 @@
 {{/* Enhanced Open Graph and Twitter Card Meta Tags */}}
 
+{{/* DNS prefetch for external services */}}
+<link rel="dns-prefetch" href="https://www.googletagmanager.com" />
+<link rel="dns-prefetch" href="https://www.google-analytics.com" />
+
+{{/* Prevent 404 pages from being indexed */}}
+{{ if eq .Kind "404" }}
+<meta name="robots" content="noindex, nofollow" />
+{{ end }}
+
 {{/* Canonical URL */}}
 <link rel="canonical" href="{{ .Permalink }}" />
 
 {{/* Open Graph URL - for all pages */}}
 <meta property="og:url" content="{{ .Permalink }}" />
 
+{{/* Open Graph Image dimensions for better social previews */}}
+<meta property="og:image:width" content="1200" />
+<meta property="og:image:height" content="630" />
+
+{{/* Twitter image alt text for accessibility */}}
+{{- $description := .Description | default .Site.Params.description -}}
+<meta name="twitter:image:alt" content="{{ $description }}" />
+
 {{/* Open Graph Type - set to "article" for posts, "website" for all other pages */}}
 {{ if eq .Section "posts" }}
   {{/* og:type="article" is already set in theme's meta/post.html */}}

layouts/partials/meta/post.html

@@ -0,0 +1,64 @@
+{{/*  These meta tags are rendered only in the posts section (i.e. in single/list page)  */}}
+{{ if eq .Section "posts" }}
+    {{ $ISO_date := dateFormat "2006-01-02T15:04:05Z0700" .Date | safeHTML }}
+    <!-- Pagination meta tags for list pages only -->
+    {{ if ne .Page.Kind "page" }}
+    {{ $paginator := .Paginate (where .Pages "Section" "blog") }}
+    {{ if $paginator }}
+    <link rel="first" href="{{ $paginator.First.URL }}" />
+    <link rel="last" href="{{ $paginator.Last.URL }}" />
+    {{ if $paginator.HasPrev }}
+    <link rel="prev" href="{{ $paginator.Prev.URL }}" />
+    {{end }}
+    {{ if $paginator.HasNext }}
+    <link rel="next" href="{{ $paginator.Next.URL }}" />
+    {{end }}
+    {{end }}
+    {{end }}
+
+    <meta property="og:type" content="article" />
+    <meta property="og:article:published_time" content={{ $ISO_date | safeHTML }} />
+    <meta property="article:published_time" content={{ $ISO_date | safeHTML }} />
+    <meta property="og:url" content="{{ .Permalink }}" />
+
+    {{ with.Site.Params.author }}
+    <meta property="og:article:author" content="{{ .name }}" />
+    <meta property="article:author" content="{{ .name }}" />
+    <meta name="author" content="{{ .name }}" />
+    {{ with.fediverseAccount }}
+    <meta name="fediverse:creator" content="{{ . }}" />{{/* ref https://blog.joinmastodon.org/2024/07/highlighting-journalism-on-mastodon/ */}}
+    {{ end }}
+    {{ end }}
+
+    {{ with.Params.category }}
+    <meta name="news_keywords" content="{{ index . 0 }}" />
+    <meta property="article:section" content="{{ index . 0 }}" />
+    {{ end }}
+
+    <script defer type="application/ld+json">
+    {
+        "@context": "https://schema.org",
+        "@type": "Article",
+        "headline": {{ .Title }},
+        "author": {
+        "@type": "Person",
+        "name": "{{ .Site.Params.github }}"
+        },
+        "datePublished": "{{ dateFormat "2006-01-02" .Date }}",
+        "description": {{ .Description }},
+        "wordCount": {{ .WordCount }},
+        "mainEntityOfPage": "True",
+        "dateModified": "{{ dateFormat "2006-01-02" .Lastmod }}",
+        "image": {
+        "@type": "ImageObject",
+        "url": "{{ with .Params.images }}{{ index . 0 | absURL }}{{ end }}",
+        "width": 1200,
+        "height": 630
+        },
+        "publisher": {
+        "@type": "Organization",
+        "name": "{{ .Site.Title }}"
+        }
+    }
+    </script>
+{{ end }}