GEO: Generalize Wikidata sameAs entity-linking into a reusable service [2h]

[isapisa]

Issue

custom JSON-LD builder classes (EntryJsonLdBuilder, AuthorJsonLdBuilder, GuideJsonLdBuilder) link entities to external authority records (Wikidata, VIAF, ORCID, WorldCat) via sameAs, each with a stable @id — something the starter's existing schema_metatag-driven Organization/WebSite/NewsArticle/WebPage baseline can't express. This issue is about pulling just that linking trait out into a reusable service, not porting whole custom pattern.

To Do

• Build a reusable service that maps an entity's Wikidata ID to sameAs links (Wikidata, VIAF, ORCID, WorldCat) and a stable @id, modeled on implementation
• Document the @id-stability convention so new projects follow it by default
• Write tests

[isapisa]

// cc @amitaibu

[mariano-dagostino]

Done as part of #1078