The finance team wants to compare paid order revenue by sales channel for every product category in the orders table.
Prepare a category-level report showing paid revenue from the web channel, paid revenue from the app channel, and total paid revenue across all channels. Orders that are not paid do not generate revenue in this report.
Every category must appear, even when it has no paid orders. Revenue for a channel with no paid sales should be 0, not NULL.
Ordering: Sort by category in ascending order.