guides: make collapsed guides single pages, recollapse refreshed nodejs

- Convert every directory-based guide from a branch bundle (_index.md =
  section) to a leaf bundle (index.md = single page). URLs and any
  co-located images are preserved; the guides are now kind=page, not
  sections.
- Re-collapse the Node.js guide on top of main's refresh (#25319): merge
  the refreshed containerize/develop/run-tests/configure-github-actions/
  secure-supply-chain/deploy topics into one page, drop the languages
  field, move tags under params ([languages]), and add aliases for the
  old /guides/nodejs/<topic>/ URLs.
- Landing: enumerate guides with RegularPagesRecursive instead of .Pages
  so every guide is listed (now that they're regular pages), including the
  nested frameworks/laravel guide that the non-recursive .Pages missed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: dvdksn