migrate to decoupled Blowfish layout, fix TOC scrollspy, and update docs

- Theme Decoupling & Cleanup:
      - Fully decoupled and vendored the Blowfish theme directly into root directories (layouts/,
  assets/, static/, data/, i18n/).
      - De-registered and cleaned up legacy Git submodules (themes/blowfish, themes/hugo-admonitions)
  from the Git index to protect the build from upstream breakages.
      - Configured .gitignore to ignore development preview symlinks (content, static,
  config/_default/menus.en.toml), build folders (public/, resources/), and locks.

    - TOC & Layout Fixes:
      - Replaced the custom layouts/_default/single.html template with the Blowfish default to restore
  native container widths and the side-by-side flex layout.
      - Restored TOC to float on the right sidebar on desktop viewports and render inline on mobile
  viewports.
      - Fixed a parameter resolution bug in layouts/partials/toc.html by checking both .Site.Params.
  smartTOC and .Site.Params.article.smartTOC (where it is defined in params.toml).
      - Upgraded the TOC scrollspy JavaScript to target all '#TableOfContents' containers on the page,
  enabling highlight tracking on both desktop and mobile layouts.

    - Documentation Updates (README.md):
      - Restored YAML front matter metadata block at the top.
      - Added detailed notes on the CI/CD build process and Gitea runner deployment targets
  (/srv/www/docs-public and /srv/www/docs-private).
      - Added a categorized and sorted "Shortcodes Quick Reference" table at the top of the shortcodes
  section (ordered by Custom, Hugo Default, and Blowfish).
      - Documented custom shortcodes (Include, Screenshot, Raw HTML) and missing Hugo default
  shortcodes (Highlight, Instagram, Param, Ref, Relref, Twitter, Vimeo, Youtube).
      - Restructured headings to ensure all sub-shortcodes are H3, removed block break tags (<br/>),
  and appended horizontal separators (---) after H2 sections.

layouts/partials/header/basic.html

@@ -0,0 +1,83 @@
+<div class="main-menu flex items-center w-full gap-2 p-1 pl-0">
+  {{ if .Site.Params.Logo }}
+    {{ $logo := resources.Get .Site.Params.Logo }}
+    {{ if $logo }}
+      <div>
+        <a href="{{ "" | relLangURL }}" class="flex">
+          <span class="sr-only">{{ .Site.Title | markdownify }}</span>
+          {{ if eq $logo.MediaType.SubType "svg" }}
+            <span class="logo object-scale-down object-left nozoom">
+              {{ $logo.Content | safeHTML }}
+            </span>
+          {{ else }}
+            <img
+              src="{{ $logo.RelPermalink }}"
+              width="{{ div $logo.Width 2 }}"
+              height="{{ div $logo.Height 2 }}"
+              class="logo max-h-20 max-w-20 object-scale-down object-left nozoom"
+              alt="">
+          {{ end }}
+        </a>
+      </div>
+    {{ end }}
+  {{ end }}
+  {{ if not .Site.Params.disableTextInHeader | default true }}
+    <a href="{{ "" | relLangURL }}" class="text-base font-medium truncate min-w-0 shrink">
+      {{ .Site.Title | markdownify }}
+    </a>
+  {{ end }}
+  <div class="flex items-center ms-auto">
+    <div class="hidden md:flex">
+      {{ partial "header/components/desktop-menu.html" . }}
+    </div>
+    <div class="flex md:hidden">
+      {{ partial "header/components/mobile-menu.html" . }}
+    </div>
+  </div>
+</div>
+
+{{ if .Site.Menus.subnavigation }}
+  <div
+    class="main-menu flex pb-3 flex-col items-end justify-between md:justify-start space-x-3 {{ if .Site.Params.Logo }}
+      -mt-[15px]
+    {{ end }}">
+    <div class="hidden md:flex items-center space-x-5">
+      {{ range .Site.Menus.subnavigation }}
+        <a
+          href="{{ .URL }}"
+          {{ if or (strings.HasPrefix .URL "http:" ) (strings.HasPrefix .URL "https:" ) }}
+            target="_blank"
+          {{ end }}
+          class="flex items-center bf-icon-color-hover">
+          {{ if .Pre }}
+            <span {{ if and .Pre .Name }}class="mr-1"{{ end }}>
+              {{ partial "icon.html" .Pre }}
+            </span>
+          {{ end }}
+          <span class="text-xs font-light" title="{{ .Title }}">
+            {{ .Name | markdownify }}
+          </span>
+        </a>
+      {{ end }}
+    </div>
+  </div>
+{{ end }}
+
+{{ if .Site.Params.highlightCurrentMenuArea }}
+  <script>
+    (function () {
+      var mainmenu = document.querySelector(".main-menu");
+      if (!mainmenu) return;
+
+      var path = window.location.pathname;
+      var links = mainmenu.querySelectorAll('a[href="' + path + '"]');
+
+      links.forEach(function (link) {
+        var targets = link.querySelectorAll("span");
+        targets.forEach(function (el) {
+          el.classList.add("active");
+        });
+      });
+    })();
+  </script>
+{{ end }}