Component home page-context chrome

Org Antora component home pages (ROOT start / hub portal) must keep page-audience and page-usage-context in the header for agents and HTML meta, but must not show that chrome to readers. Author and contributor metadata belong at the end of the page.

@antora-supplemental/page-context 0.5 implements this when :page-context-surface: component-home is set, or when Antora supplies page-module=ROOT with page-relative-src-path=index.adoc. Section landings keep normal lead orientation.

House policy: general/documentation.md. Skill: antora-org-site.