Function resolve_order_status 

pub fn resolve_order_status(
    status: PolymarketOrderStatus,
    event_type: PolymarketEventType,
) -> OrderStatus

Resolves the Nautilus order status from Polymarket status and event type.

Venue-initiated cancellations arrive as status=Invalid, event_type=Cancellation (e.g. sport market resolution). These map to Canceled, not Rejected.