s&box: INetworkListener.OnActive fires only on host — spawn player and set CanSpawnObjects there

Developers new to s&box networking often try to spawn players in OnStart or via client-side logic. In s&box, Component.INetworkListener.OnActive(Connection channel) is the correct hook for player spawning — but it only fires on the host. Calling spawn logic from the client or from OnStart results in players not appearing or authority errors.