Notify online firm members in-game when a new employee joins the firm (employment offer accepted / hire confirmed).
Built on the firm notification system (PAR-94) — call notifyFirm(firmId, "business.notify.employee.joined", "player", name) after a successful join.
Technical notes — the join happens in FirmRequestServiceImpl (offer accept) / FirmStaffServiceImpl. There's already a partial broadcast to online staff in RequestCommands.offer (the offer, not the accept); this is about the accept completing. Fire the notification once the employee row is created. Skip notifying the new hire themselves via notifyFirmExcept.