V-subregion annotations

Rewritten from docs/v_region_substructure_audit.md.

Migration placeholder

This page is a placeholder. Content lands in Phase 4 of the migration plan documented in docs/docs_mkdocs_migration_plan.md.

Until then, see the corresponding live page on the existing documentation site at mutejester.github.io/GenAIRR or the source markdown referenced above (if any).