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/_default/_markup/render-blockquote.html

@@ -0,0 +1,93 @@
+{{- /* To customize your own admonitions, you can do the following:
+
+  1. Change colors
+
+      Define your colors in `assets/css/custom.css` using the variables from:
+      https://github.com/nunocoracao/blowfish/blob/main/assets/css/components/admonition.css
+
+      Example:
+      ```
+      :root {
+          --adm-note-bg: red;
+      }
+      html.dark {
+          --adm-note-bg: green;
+      }
+      ```
+
+      This will update the background color for light and dark mode.
+
+  2. Change icons and type settings
+
+      You can override the default type and icon mappings by creating your own
+      `impls/hooks/admonition-maps.html` in your `layouts` folder.
+      This allows you to assign different icons or styles for each admonition type.
+*/ -}}
+
+{{- if eq .Type "alert" -}}
+  {{- $maps := partialCached "impls/hooks/admonition-maps.html" . -}}
+  {{- $typeMap := $maps.typeMap -}}
+  {{- $iconMap := $maps.iconMap -}}
+
+  {{- $rawType := .AlertType | lower -}}
+  {{- $normalizedType := index $typeMap $rawType | default $rawType -}}
+  {{- $iconName := .Attributes.icon | default (index $iconMap $normalizedType) | default "circle-info" -}}
+
+  {{- $admonitionTitle := .AlertTitle | default ((i18n (printf "admonition.%s" $normalizedType) | default $normalizedType) | title) -}}
+
+  {{- $containerClass := "admonition relative overflow-hidden rounded-lg border-l-4 my-3 px-4 py-3 shadow-sm" -}}
+  {{- $headerClass := "flex items-center gap-2 font-semibold text-inherit" -}}
+  {{- $contentClass := "admonition-content mt-3 text-base leading-relaxed text-inherit" -}}
+
+  {{- $isCollapsible := in (slice "+" "-") .AlertSign -}}
+  {{- if $isCollapsible -}}
+    <details
+      class="{{ $containerClass }} group"
+      data-type="{{ $normalizedType }}"
+      {{ if eq .AlertSign "+" }}open{{ end }}>
+      <summary class="{{ $headerClass }} cursor-pointer">
+        <div class="flex shrink-0 h-5 w-5 items-center justify-center text-lg">
+          {{- partial "icon.html" $iconName -}}
+        </div>
+        <div class="grow">
+          {{ $admonitionTitle }}
+        </div>
+        <div
+          class="ms-auto flex h-5 w-5 items-center justify-center transition-transform ease-in-out -rotate-90 group-open:rotate-0 print:hidden">
+          {{- partial "icon.html" "chevron-down" -}}
+        </div>
+      </summary>
+      {{- if .Text -}}
+        <div class="{{ $contentClass }}">
+          {{- .Text | safeHTML -}}
+        </div>
+      {{- end -}}
+    </details>
+  {{- else -}}
+    <div class="{{ $containerClass }}" data-type="{{ $normalizedType }}">
+      <div class="{{ $headerClass }}">
+        <div class="flex shrink-0 h-5 w-5 items-center justify-center text-lg">
+          {{- partial "icon.html" $iconName -}}
+        </div>
+        <div class="grow">
+          {{ $admonitionTitle }}
+        </div>
+      </div>
+      {{- if .Text -}}
+        <div class="{{ $contentClass }}">
+          {{- .Text | safeHTML -}}
+        </div>
+      {{- end -}}
+    </div>
+  {{- end -}}
+
+{{- else -}}
+  <blockquote 
+  {{- range $k, $v := .Attributes -}}
+    {{- if $v -}}
+      {{- printf " %s=%q" $k ($v | transform.HTMLEscape) | safeHTMLAttr -}}
+    {{- end -}}
+  {{- end -}}>
+    {{- .Text | safeHTML -}}
+  </blockquote>
+{{- end -}}