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.

assets/js/zen-mode.js

@@ -0,0 +1,67 @@
+function _toggleZenMode(zendModeButton, options = { scrollToHeader: true }) {
+  // Nodes selection
+  const body = document.querySelector("body");
+  const footer = document.querySelector("footer");
+  const tocRight = document.querySelector(".toc-right");
+  const tocInside = document.querySelector(".toc-inside");
+  const articleContent = document.querySelector(".article-content");
+  const header = document.querySelector("#single_header");
+
+  // Add semantic class into body tag
+  body.classList.toggle("zen-mode-enable");
+
+  // Show/Hide 'toc right' and 'toc inside'
+  if (tocRight) tocRight.classList.toggle("lg:block");
+  if (tocInside) tocInside.classList.toggle("lg:hidden");
+
+  // Change width of article content
+  articleContent.classList.toggle("max-w-fit");
+  articleContent.classList.toggle("max-w-prose");
+
+  // Change width of article title and footer
+  header.classList.toggle("max-w-full");
+  header.classList.toggle("max-w-prose");
+  footer.classList.toggle("max-w-full");
+  footer.classList.toggle("max-w-prose");
+
+  // Read i18n title from data-attributes
+  const titleI18nDisable = zendModeButton.getAttribute("data-title-i18n-disable");
+  const titleI18nEnable = zendModeButton.getAttribute("data-title-i18n-enable");
+
+  if (body.classList.contains("zen-mode-enable")) {
+    // Persist configuration
+    //localStorage.setItem('blowfish-zen-mode-enabled', 'true');
+
+    // Change title to enable
+    zendModeButton.setAttribute("title", titleI18nEnable);
+    // Auto-scroll to title article
+    if (options.scrollToHeader) {
+      window.scrollTo(window.scrollX, header.getBoundingClientRect().top - 90);
+    }
+  } else {
+    //localStorage.setItem('blowfish-zen-mode-enabled', 'false');
+    zendModeButton.setAttribute("title", titleI18nDisable);
+    if (options.scrollToHeader) {
+      document.querySelector("body").scrollIntoView();
+    }
+  }
+}
+
+function _registerZendModeButtonClick(zendModeButton) {
+  zendModeButton.addEventListener("click", function (event) {
+    event.preventDefault();
+
+    // Toggle zen-mode
+    _toggleZenMode(zendModeButton);
+  });
+}
+
+(function init() {
+  window.addEventListener("DOMContentLoaded", (event) => {
+    // Register click on 'zen-mode-button' node element
+    const zendModeButton = document.getElementById("zen-mode-button");
+    if (zendModeButton !== null && zendModeButton !== undefined) {
+      _registerZendModeButtonClick(zendModeButton);
+    }
+  });
+})();