Build documentation action

Renders the canonical Markdown hierarchy in docs/ into an existing static publish directory.

bash actions/build.docs.sh \
  --source docs \
  --output static \
  --site-root /debian

Pandoc is an explicit prerequisite. The action never installs it; the Pages workflow supplies it. Canonical pages require title and section front matter, and their optional source_path must resolve in the checkout.

Option Purpose
--source docs Selects the canonical Markdown source hierarchy.
--output static Writes rendered HTML and assets to the selected generated directory.
--site-root /debian Generates project-site links for https://devs-guide.github.io/debian/. Use the actual project path when validating another Pages site.

Legacy files retained at the old docs/ paths are not rendered as current public pages. They remain in the repository while their content is migrated into the canonical hierarchy.