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/components/a11y.html

@@ -0,0 +1,88 @@
+{{- $prefix := .prefix | default "" -}}
+<div class="flex items-center">
+  <button
+    id="{{ $prefix }}a11y-toggle"
+    aria-label="Open accessibility panel"
+    aria-expanded="false"
+    type="button"
+    class="bf-icon-color-hover"
+    role="button"
+    aria-pressed="false">
+    {{ partial "icon.html" "a11y" }}
+  </button>
+
+  <div id="{{ $prefix }}a11y-overlay" class="fixed inset-0 hidden" style="z-index:9999;"></div>
+
+  <div
+    id="{{ $prefix }}a11y-panel"
+    role="dialog"
+    aria-labelledby="{{ $prefix }}a11y-panel-title"
+    class="a11y-panel-enter fixed hidden p-6 top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 w-80 rounded-lg shadow-xl bg-neutral-50 dark:bg-neutral-800 border border-neutral-300 dark:border-neutral-700"
+    style="min-width: 20rem; z-index:9999;">
+    <div class="flex items-center justify-between mb-6">
+      <h3
+        id="{{ $prefix }}a11y-panel-title"
+        class="text-lg font-semibold text-neutral-900 dark:text-neutral-100">
+        {{ i18n "a11y.title" }}
+      </h3>
+      <button
+        id="{{ $prefix }}a11y-close"
+        class="text-neutral-500 hover:text-neutral-700 dark:text-neutral-400 dark:hover:text-neutral-200"
+        aria-label="Close a11y panel">
+        <svg class="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+          <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12" />
+        </svg>
+      </button>
+    </div>
+
+    <div class="space-y-5">
+      {{ $toggles := slice }}
+      {{ $shouldDisableBlur := or site.Params.homepage.layoutBackgroundBlur site.Params.article.layoutBackgroundBlur site.Params.list.layoutBackgroundBlur }}
+      {{ $shouldDisableBackgroundImage := or
+        (eq site.Params.homepage.layout "background")
+        (eq site.Params.article.heroStyle "background")
+        (eq site.Params.list.heroStyle "background")
+        (eq site.Params.taxonomy.heroStyle "background")
+        (eq site.Params.term.heroStyle "background")
+      }}
+      {{ if $shouldDisableBlur }}
+        {{ $toggles = $toggles | append (dict "id" (print $prefix "disable-blur") "label" (i18n "a11y.disable_blur")) }}
+      {{ end }}
+      {{ if $shouldDisableBackgroundImage }}
+        {{ $toggles = $toggles | append (dict "id" (print $prefix "disable-images") "label" (i18n "a11y.disable_images")) }}
+      {{ end }}
+      {{- $toggles = $toggles | append
+        (dict "id" (print $prefix "underline-links") "label" (i18n "a11y.show_link_underline"))
+        (dict "id" (print $prefix "zen-mode") "label" (i18n "article.zen_mode_title.enable"))
+      -}}
+
+      {{- range $toggles }}
+        <div class="flex items-center justify-between">
+          <label for="{{ .id }}" class="text-sm font-medium text-neutral-700 dark:text-neutral-300">
+            {{ .label }}
+          </label>
+          <div class="ios-toggle">
+            <input type="checkbox" id="{{ .id }}">
+          </div>
+        </div>
+      {{- end }}
+
+
+      <div class="flex items-center justify-between">
+        <label
+          for="{{ $prefix }}font-size-select"
+          class="text-sm font-medium text-neutral-700 dark:text-neutral-300">
+          {{ i18n "a11y.font_size" }}
+        </label>
+        <select
+          id="{{ $prefix }}font-size-select"
+          class="border rounded-lg px-3 py-1.5 pr-8 text-neutral-900 text-sm dark:bg-neutral-700 dark:text-neutral-200 focus:ring-primary-500 focus:border-primary-500">
+          {{ $fontSizes := slice "default" "12px" "14px" "16px" "18px" "20px" "22px" "24px" }}
+          {{ range $fontSizes }}
+            <option value="{{ . }}">{{ . }}</option>
+          {{ end }}
+        </select>
+      </div>
+    </div>
+  </div>
+</div>