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/shortcodes/github.html

@@ -0,0 +1,83 @@
+{{ $id := delimit (slice "github" (partial "functions/uid.html" .)) "-" }}
+{{- $githubURL := print "https://api.github.com/repos/" (.Get "repo") -}}
+{{- $githubThumbnailURL := print "https://opengraph.githubassets.com/0/" (.Get "repo") -}}
+{{- $showThumbnail := .Get "showThumbnail" | default true -}}
+{{- $repoColors := hugo.Data.repoColors -}}
+{{- $githubData := dict -}}
+{{- with try (resources.GetRemote $githubURL) -}}
+  {{- with .Err -}}
+    {{- warnf "github shortcode: failed to fetch remote resource from %q: %s" $githubURL $.Position -}}
+  {{- else with .Value -}}
+    {{- $githubData = . | transform.Unmarshal -}}
+  {{- else -}}
+    {{- warnf "github shortcode: unable to get remote resource from %q: %s" $githubURL $.Position -}}
+  {{- end -}}
+{{- end -}}
+
+{{- with $githubData -}}
+  <div class="github-card-wrapper">
+    <a id="{{ $id }}" target="_blank" href="{{ .html_url }}" class="cursor-pointer">
+      <div
+        class="w-full md:w-auto p-0 m-0 border border-neutral-200 dark:border-neutral-700 border rounded-md shadow-2xl">
+        {{- if $showThumbnail -}}
+          <div class="w-full nozoom">
+            <img
+              src="{{ $githubThumbnailURL }}"
+              alt="GitHub Repository Thumbnail"
+              class="nozoom mt-0 mb-0 w-full h-full object-cover">
+          </div>
+        {{- end -}}
+
+
+        <div class="w-full md:w-auto pt-3 p-5">
+          <div class="flex items-center">
+            <span class="text-2xl text-neutral-800 dark:text-neutral me-2">
+              {{ partial "icon.html" "github" }}
+            </span>
+            <div
+              id="{{ $id }}-full_name"
+              class="m-0 font-bold text-xl text-neutral-800 decoration-primary-500 hover:underline hover:underline-offset-2 dark:text-neutral">
+              {{ .full_name | markdownify }}
+            </div>
+          </div>
+
+          <p id="{{ $id }}-description" class="m-0 mt-2 text-md text-neutral-800 dark:text-neutral">
+            {{ .description | markdownify }}
+          </p>
+
+          <div class="m-0 mt-2 flex items-center">
+            <span class="mr-1 inline-block h-3 w-3 rounded-full language-dot" data-language="{{ .language | default "default" }}"></span>
+            <div class="m-0 mr-5 text-md text-neutral-800 dark:text-neutral">
+              {{ if .language }}{{ .language }}{{ else }}null{{ end }}
+            </div>
+
+            <span class="text-md mr-1 text-neutral-800 dark:text-neutral">
+              {{ partial "icon.html" "star" }}
+            </span>
+            <div id="{{ $id }}-stargazers" class="m-0 mr-5 text-md text-neutral-800 dark:text-neutral">
+              {{ .stargazers_count }}
+            </div>
+
+            <span class="text-md mr-1 text-neutral-800 dark:text-neutral">
+              {{ partial "icon.html" "fork" }}
+            </span>
+            <div id="{{ $id }}-forks" class="m-0 mr-5 text-md text-neutral-800 dark:text-neutral">
+              {{ .forks }}
+            </div>
+          </div>
+        </div>
+      </div>
+      {{ $fetchRepo := resources.Get "js/fetch-repo.js" }}
+      {{ $fetchRepo = $fetchRepo | resources.Minify | resources.Fingerprint ($.Site.Params.fingerprintAlgorithm | default "sha512") }}
+      <script
+        async
+        type="text/javascript"
+        src="{{ $fetchRepo.RelPermalink }}"
+        integrity="{{ $fetchRepo.Data.Integrity }}"
+        data-repo-url="{{ $githubURL }}"
+        data-repo-id="{{ $id }}"></script>
+    </a>
+  </div>
+{{- else -}}
+  {{ warnf "github shortcode: unable to fetch %q: %s" $githubURL .Position }}
+{{- end -}}