SQL: Latest Order Per Customer (ROW_NUMBER)

> This problem is paper-only - see explanation for the canonical SQL solution. Given `Orders(id, customer_id, order_date, total)`, return the **latest order per customer**. If a customer has multiple orders on the same most-recent date, pick the one with the largest `id` as tiebreaker. Sort the result by customer_id ascending. **For the auto-grader:** return `[{ id, customer_id, order_date, total }]`.