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/shortcodes/tabs.js

@@ -0,0 +1,59 @@
+function initTabs() {
+  tabClickHandler = (event) => {
+    const button = event.target.closest(".tab__button");
+    if (!button) return;
+
+    const container = button.closest(".tab__container");
+    const tabIndex = parseInt(button.dataset.tabIndex);
+    const tabLabel = button.dataset.tabLabel;
+    const group = container.dataset.tabGroup;
+
+    if (group) {
+      const allGroupContainers = document.querySelectorAll(`.tab__container[data-tab-group="${group}"]`);
+
+      allGroupContainers.forEach((groupContainer) => {
+        const targetButton = Array.from(groupContainer.querySelectorAll(".tab__button")).find(
+          (btn) => btn.dataset.tabLabel === tabLabel,
+        );
+
+        if (targetButton) {
+          const targetIndex = parseInt(targetButton.dataset.tabIndex);
+          activateTab(groupContainer, targetIndex);
+        }
+      });
+    } else {
+      activateTab(container, tabIndex);
+    }
+  };
+
+  document.addEventListener("click", tabClickHandler);
+}
+
+function activateTab(container, activeIndex) {
+  const buttons = container.querySelectorAll(".tab__button");
+  const panels = container.querySelectorAll(".tab__panel");
+
+  buttons.forEach((btn, index) => {
+    if (index === activeIndex) {
+      btn.classList.add("tab--active");
+      btn.setAttribute("aria-selected", "true");
+    } else {
+      btn.classList.remove("tab--active");
+      btn.setAttribute("aria-selected", "false");
+    }
+  });
+
+  panels.forEach((panel, index) => {
+    if (index === activeIndex) {
+      panel.classList.add("tab--active");
+    } else {
+      panel.classList.remove("tab--active");
+    }
+  });
+}
+
+if (document.readyState === "loading") {
+  document.addEventListener("DOMContentLoaded", initTabs);
+} else {
+  initTabs();
+}