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/_default/llms.txt

@@ -0,0 +1,41 @@
+{{- /* Recursive printer for sections */ -}}
+{{- define "llms_print_section" -}}
+{{- $section := .section -}}
+{{- $depth := .depth -}}
+{{- if or (gt (len $section.RegularPages) 0) (gt (len $section.Sections) 0) -}}
+{{- $hashes := strings.Repeat (add $depth 1) "#" }}
+
+{{ printf "%s %s" $hashes $section.Title }}
+
+{{- /* Pages in this section */ -}}
+{{- range $p := $section.RegularPages }}
+  {{- if and (not $p.Params.searchHidden) (ne $p.Layout `archives`) (ne $p.Layout `search`) }}
+- [{{ $p.Title }}]({{ $p.Permalink }})
+  {{- end -}}
+{{- end -}}
+
+{{- /* Recurse into subsections */ -}}
+{{- range $s := $section.Sections -}}
+{{- template "llms_print_section" (dict "section" $s "depth" (add $depth 1)) -}}
+{{- end -}}
+{{- end -}}
+{{- end -}}
+
+{{- /* Main template starts here */ -}}
+# {{ site.Title }}
+
+{{- /* Pages not in any section */ -}}
+{{- $orphans := where site.RegularPages "Section" "" -}}
+{{ if gt (len $orphans) 0 }}
+
+{{- range $p := $orphans -}}
+  {{ if and (not $p.Params.searchHidden) (ne $p.Layout `archives`) (ne $p.Layout `search`) (not $p.IsHome) }}
+- [{{ $p.Title }}]({{ $p.Permalink }})
+  {{- end -}}
+{{- end -}}
+
+{{- end -}}
+
+{{- range site.Sections -}}
+{{- template "llms_print_section" (dict "section" . "depth" 1) -}}
+{{- end }}