Migrate WordPress site to Hugo

Replaces the WordPress 7.0.2 / HitMag site with a static Hugo build,
deployed by Gitea Actions over rsync/SSH.

Content: 26 files (9 pages + 17 posts) as Markdown page bundles, plus
127 of 165 media attachments. The remaining 38 are media-library
leftovers that appear nowhere on the live site; they are listed in
MIGRATION.md.

The WXR export contains neither media binaries nor widgets, so both were
recovered from the live host before it is retired:
  - tools/fetch_media.py downloads all uploads, capping them at 2000px
  - tools/build_data.py scrapes the "Unsere Mitglieder" and
    "In Erinnerung" widgets into data/*.yaml

TablePress' six Termine tables became data/termine.yaml, rendered with
the newest year expanded and earlier years collapsed. Old permalinks are
not preserved (clean slugs, no redirects, as agreed).

Custom layouts, no third-party theme. Plain CSS, since the pinned Hugo
0.164.0 is the non-extended build and cannot compile Sass.

Verified: clean build with zero warnings, 718 internal links checked and
none broken, no surviving wp-content URLs.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

layouts/_shortcodes/gallery.html

@@ -0,0 +1,32 @@
+{{- /*
+  Responsive image grid.
+    {{< gallery "a.jpg" "b.jpg" >}}   explicit, ordered
+    {{< gallery >}}                   every image resource of the page
+  Thumbnails link to the full-size original.
+*/ -}}
+{{- $page := .Page -}}
+{{- $images := slice -}}
+{{- if .Params -}}
+  {{- range .Params -}}
+    {{- with $page.Resources.GetMatch . -}}
+      {{- $images = $images | append . -}}
+    {{- else -}}
+      {{- warnf "gallery: %q not found in %s" . $page.Path -}}
+    {{- end -}}
+  {{- end -}}
+{{- else -}}
+  {{- $images = $page.Resources.ByType "image" -}}
+{{- end -}}
+
+{{- if $images -}}
+<div class="gallery">
+  {{- range $images }}
+    {{- $thumb := .Fill "400x300 Center webp q80" }}
+    {{- $full := .Resize "1600x webp q82" }}
+    <a class="gallery-item" href="{{ $full.RelPermalink }}">
+      <img src="{{ $thumb.RelPermalink }}" width="{{ $thumb.Width }}" height="{{ $thumb.Height }}"
+           alt="" loading="lazy" decoding="async">
+    </a>
+  {{- end }}
+</div>
+{{- end -}}