Cross-provider fixture grouping is a backend display projection

Status: Superseded in part by ADR-0027.

Provider fixtures retain their own Provider Fixture Identity even when Bifrost explicitly supplies a Betfair event ID. A backend projection may use that current Cross-Provider Fixture Link to produce the same Fixture Display Group for admin and player APIs: the linked group shows both providers' markets, while an unlinked Bifrost fixture remains a complete standalone group using Bifrost's names and markets. The frontend only renders the projection. Provider-owned market identities remain distinct and the link never affects market ownership, routing, orders, exposure, or settlement. ADR-0027 refines the persisted catalogue projection: provider sources may share one CatalogueMatch, but the exact fixture link never establishes tournament equivalence or authorizes a sibling cascade.