The CRM team wants to display the most recent order for each registered customer.
Using customers and orders, identify each customer's latest order by order_ts. If two orders have the same latest timestamp, choose the one with the larger order_id.
Orders with a missing timestamp cannot be ranked and should be ignored. Guest orders and orders associated with unregistered customer IDs should not appear. Customers without any dated orders should also be excluded.
Ordering: Sort by customer_id in ascending order.