Get League Superlatives
The league’s all-time superlatives, as computed by whatever round_closed
reporter is subscribed to it — the newest superlatives-family document
(schema_version ending in -superlatives/v1) produced by one of the league’s
own subscriptions. This backs the league-leaders banner, so it is visible to
anyone who can see the league and deliberately drops the owner/team scoping the
raw /reporters/* endpoints enforce (a reporter’s runs are otherwise visible only
to their requester). The payload is the reporter’s own document, identified on
the client by its schema_version; no reporter id is hardcoded. Returns 204
when no such reporter has a completed run yet (the banner then shows nothing).