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.

config/_default_original/menus.en.toml

@@ -0,0 +1,57 @@
+# -- Main Menu --
+# The main menu is displayed in the header at the top of the page.
+# Acceptable parameters are name, pageRef, page, url, title, weight.
+# 
+# The simplest menu configuration is to provide:
+#   name = The name to be displayed for this menu link
+#   pageRef = The identifier of the page or section to link to
+#
+# By default the menu is ordered alphabetically. This can be
+# overridden by providing a weight value. The menu will then be
+# ordered by weight from lowest to highest.
+
+[[main]]
+ name = "projects"
+ pageRef = "projects"
+ weight = 10
+
+[[main]]
+ name = "posts"
+ pageRef = "posts"
+ weight = 20
+
+[[main]]
+ name = "stream"
+ pageRef = "stream"
+ weight = 30
+
+[[subnavigation]]
+  name = "lab"
+  pageRef = "lab_setup"
+  weight = 10
+
+[[subnavigation]]
+  name = "resume"
+  pageRef = "resume"
+  weight = 20
+
+# [[subnavigation]]
+#   name = "My Awesome Category"
+#   pageRef = "categories/awesome"
+#   weight = 20
+
+# -- Footer Menu --
+# The footer menu is displayed at the bottom of the page, just before
+# the copyright notice. Configure as per the main menu above.
+
+# config/_default/menus.toml
+
+# [[footer]]
+#   name = "Tags"
+#   pageRef = "tags"
+#   weight = 10
+
+# [[footer]]
+#   name = "Categories"
+#   pageRef = "categories"
+#   weight = 20