> This problem is paper-only - see explanation for the canonical SQL solution.
Given `Sales(region, quarter, amount)`, pivot the data into one row per region with one column per quarter (`q1`, `q2`, `q3`, `q4`). Use 0 for missing buckets. Sort by region ascending.
**For the auto-grader:** return `[{ region, q1, q2, q3, q4 }]`. `quarter` is one of `"Q1"|"Q2"|"Q3"|"Q4"`.