Function
The route's own copy, path and locale
A Next Metadata object with canonical, alternates, Open Graph and Twitter composed
One builder rather than four copies inside each generateMetadata. Head tags
render invisibly, so a page that quietly lost its og:locale:alternate would
go unnoticed for as long as nobody inspected it — centralising the shape means
there is exactly one implementation to test.
twitter:site and twitter:creator are deliberately absent: there is no
account, and an empty handle carries no information.
The image URL is the route's own opengraph-image convention path, declared
relative so metadataBase absolutizes it.
Composes the metadata a single route publishes about itself.