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/analytics/umami.html

@@ -0,0 +1,29 @@
+{{/* prettier-ignore-start */}}
+{{ if isset site.Params.umamiAnalytics "domain" }}
+  <script
+    data-id="umami-script"
+    async
+    src="https://{{ site.Params.umamiAnalytics.domain }}/{{ with site.Params.umamiAnalytics.scriptName }}{{ . }}{{ else }}script.js{{ end }}"
+    data-website-id="{{ site.Params.umamiAnalytics.websiteid }}"
+    {{ with site.Params.umamiAnalytics.dataDomains }}data-domains="{{ . }}"{{ end }}
+    data-do-not-track="{{ site.Params.umamiAnalytics.doNotTrack | default false }}"></script>
+{{ else }}
+  <script
+    data-id="umami-script"
+    async
+    src="https://analytics.umami.is/script.js"
+    data-website-id="{{ site.Params.umamiAnalytics.websiteid }}"
+    data-do-not-track="{{ site.Params.umamiAnalytics.doNotTrack | default false }}"></script>
+{{ end }}
+{{/* prettier-ignore-end */}}
+
+{{ if .Site.Params.umamiAnalytics.enableTrackEvent | default true }}
+  <script type="text/javascript">
+    document.querySelector('script[data-id="umami-script"]').addEventListener("load", function () {
+      const type = document.head.querySelector('meta[property = "og:type"]').getAttribute("content");
+      let title = document.head.querySelector('meta[property = "og:title"]').getAttribute("content");
+      let url = document.head.querySelector('meta[property = "og:url"]').getAttribute("content");
+      umami.track(type + ":view", { title: title, url: url });
+    });
+  </script>
+{{ end }}