Export isSparkTableHeader from content-registry and use it in both CLI
and frontend table parsing. Add resolveContentRef to resolve content
references consistently. Write processed registry content back to the
file index so browser mode renders identically to CLI mode.
Relocate spark table logic from the block processor to a dedicated
directive scanner. This allows spark tables to be treated as
`:md-table` directives and ensures they are processed in a second pass
after the content index is fully populated.
Introduce a new documentation set for Journal server functionality,
including a dropdown selector in the DocDialog to switch between
"directives" and "journal" documentation modes.
Update the spark button injection to use `data-spark` slugs on
`md-table` elements instead of manual table parsing. This improves
reliability by leveraging the slug generated during markdown
rendering.