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/_partials/header.html

@@ -0,0 +1,38 @@
+<header class="site-header">
+  <div class="container site-branding">
+    <a class="site-logo" href="{{ "/" | relURL }}" rel="home">
+      {{ with resources.Get site.Params.logo }}
+        {{ $l := .Resize "160x png" }}
+        <img src="{{ $l.RelPermalink }}" width="{{ $l.Width }}" height="{{ $l.Height }}"
+             alt="Wappen des Motorradclub Giebelwald">
+      {{ end }}
+    </a>
+    <div class="site-titles">
+      <p class="site-title"><a href="{{ "/" | relURL }}" rel="home">{{ site.Title }}</a></p>
+      <p class="site-tagline">{{ site.Params.tagline }}</p>
+    </div>
+  </div>
+
+  {{ with resources.Get site.Params.banner }}
+    {{ $banner := .Resize "1600x webp q80" }}
+    <img class="site-banner" src="{{ $banner.RelPermalink }}"
+         width="{{ $banner.Width }}" height="{{ $banner.Height }}"
+         alt="" loading="eager" decoding="async">
+  {{ end }}
+
+  <nav class="site-nav" aria-label="Hauptnavigation">
+    <div class="container">
+      <input type="checkbox" id="nav-toggle" class="nav-toggle">
+      <label for="nav-toggle" class="nav-toggle-label">
+        <span aria-hidden="true">☰</span> Menü
+      </label>
+      <ul class="nav-list">
+        <li><a href="{{ "/" | relURL }}"{{ if .IsHome }} aria-current="page"{{ end }}>Start</a></li>
+        {{ range site.Menus.main }}
+          {{ $active := or ($.IsMenuCurrent "main" .) ($.HasMenuCurrent "main" .) }}
+          <li><a href="{{ .URL }}"{{ if $active }} aria-current="page"{{ end }}>{{ .Name }}</a></li>
+        {{ end }}
+      </ul>
+    </div>
+  </nav>
+</header>