List tournament staff

Returns the tournament's delegated staff, resolved by slug. The host is not included - host authority comes from the host record rather than a staff row, so an empty list means no delegated staff, not no organizers. Reading requires tournaments.tournament_admin:read on the key AND that the caller manages the tournament (host, tournament ADMIN, or tournament MODERATOR); adding and removing staff requires ADMIN. Tournament API access is gated at api_pro on the tournament HOST OWNER's personal developer plan. An organization holding a consumer subscription does not satisfy this - the developer plan ladder has no organization arm.