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/timelineItem.html

@@ -0,0 +1,37 @@
+{{ $icon := .Get "icon" | default "check" }}
+{{ $md := .Get "md" | default false }}
+{{ $header := .Get "header" }}
+{{ $badge := .Get "badge" }}
+{{ $subheader := .Get "subheader" }}
+<li>
+  <div class="flex">
+    <div
+      class="bg-primary-500 dark:bg-primary-300 text-neutral-50 dark:text-neutral-700 min-w-[30px] h-8 text-2xl flex items-center justify-center rounded-full ltr:-ml-12 rtl:-mr-[79px] mt-5">
+      {{ partial "icon" $icon }}
+    </div>
+    <div class="block p-6 rounded-lg shadow-2xl flex-1 ms-6 mb-10 break-words">
+      <div class="flex justify-between">
+        {{ if $header }}
+          <h2 class="mt-0">{{ $header }}</h2>
+        {{ end }}
+        {{ if $badge }}
+          <h3 class="">
+            {{ partial "badge" $badge }}
+          </h3>
+        {{ end }}
+      </div>
+      {{ if $subheader }}
+        <h4 class="mt-0">
+          {{ $subheader }}
+        </h4>
+      {{ end }}
+      <div class="mb-6">
+        {{ if $md }}
+          {{- .Inner | markdownify -}}
+        {{ else }}
+          {{- .Inner -}}
+        {{ end }}
+      </div>
+    </div>
+  </div>
+</li>