Median Order Value by Region

Uber Eats analysts prefer medians over averages because a few huge orders skew the mean. Neither MySQL nor Postgres lets you compute a median with a simple aggregate that works in both, so it must be built from window functions. For each region, return `region`, `order_count` (number of orders) and `median_order_value` (rounded to 2 decimals). For an odd number of orders the median is the middle value; for an even number it is the average of the two middle values. Order the results by `region` ascending.