Retrieves the file relations for a given entity, each including the linked file's details. Results are paginated.

Staff access is scoped to the linked entity: a staff sees relations for any entity they can access, regardless of who uploaded the file. Client access is scoped to the client's own relations. In both cases, no access to the entity is not an error — it returns an empty list (total: 0), indistinguishable from the entity genuinely having no relations.

Available for Staff and Client tokens.