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.

i18n/en.yaml

@@ -0,0 +1,105 @@
+global:
+  language: "EN"
+
+article:
+  anchor_label: "Anchor"
+  date: "{{ .Date }}"
+  date_updated: "Updated: {{ .Date }}"
+  draft: "Draft"
+  edit_title: "Edit content"
+  reading_time:
+    one: "{{ .Count }} min"
+    other: "{{ .Count }} mins"
+  reading_time_title: "Reading time"
+  table_of_contents: "Table of Contents"
+  word_count:
+    one: "{{ .Count }} word"
+    other: "{{ .Count }} words"
+  views:
+    one: "{{ .Count }} view"
+    other: "{{ .Count }} views"
+  likes:
+    one: "{{ .Count }} like"
+    other: "{{ .Count }} likes"
+  part_of_series: "This article is part of a series."
+  part: "Part"
+  this_article: "This Article"
+  related_articles: "Related"
+  reply_by_email: "Reply by Email"
+  reply_to: "Reply to {{ .Title }}"
+  zen_mode_title:
+    enable: "Enable zen mode"
+    disable: "Disable zen mode"
+
+a11y:
+  title: "Accessibility settings"
+  disable_blur: "Disable blur"
+  disable_images: "Disable background image"
+  show_link_underline: "Show link underline"
+  font_size: "Font size"
+
+author:
+  byline_title: "Author"
+
+code:
+  copy: "Copy"
+  copied: "Copied"
+
+error:
+  404_title: "Page Not Found :confused:"
+  404_error: "Error 404"
+  404_description: "It seems that the page you've requested does not exist."
+
+footer:
+  dark_appearance: "Switch to dark appearance"
+  light_appearance: "Switch to light appearance"
+  powered_by: "Powered by {{ .Hugo }} & {{ .Theme }}"
+
+list:
+  externalurl_title: "Link to external site"
+  no_articles: "There are no articles to list here yet."
+
+nav:
+  scroll_to_top_title: "Scroll to top"
+  skip_to_main: "Skip to main content"
+
+search:
+  open_button_title: "Search (/)"
+  close_button_title: "Close (Esc)"
+  input_placeholder: "Search"
+
+sharing:
+  email: "Send via email"
+  facebook: "Share on Facebook"
+  line: "Share on LINE"
+  linkedin: "Share on LinkedIn"
+  pinterest: "Pin on Pinterest"
+  reddit: "Submit to Reddit"
+  twitter: "Tweet on Twitter"
+  bluesky: "Post on Bluesky"
+  whatsapp: "Share via WhatsApp"
+  telegram: "Share via Telegram"
+  mastodon: "Share via Mastodon"
+
+shortcode:
+  recent_articles: "Recent"
+
+recent:
+  show_more: "Show More"
+
+admonition:
+  abstract: "Abstract"
+  bug: "Bug"
+  caution: "Caution"
+  danger: "Danger"
+  example: "Example"
+  failure: "Failure"
+  important: "Important"
+  info: "Info"
+  note: "Note"
+  question: "Question"
+  quote: "Quote"
+  success: "Success"
+  tip: "Tip"
+  todo: "Todo"
+  warning: "Warning"