Transforming Lists with list_transform

`list_transform` applies a function to every element of a list and returns a new list with the results. Think of it like a map operation.

The syntax uses a `lambda` expression:

SELECT list_transform([1, 2, 3], lambda x : x * 10)
-- [10, 20, 30]

Lambda expressions start with the keyword `lambda`, followed by a parameter name, a colon, and the expression to evaluate.

You can use this on table columns too. For example, adding 10% tax to every price in a list:

SELECT customer, list_transform(prices, lambda p : round(p * 1.1, 2)) AS taxed
FROM orders

`NULL` elements stay `NULL` after transformation. The return type of the new list is determined by the lambda expression.

The sample table stores `items` and `prices` as parallel lists. That means the first item belongs with the first price, the second item belongs with the second price, and so on. This is compact, but position-dependent data can be fragile if the lists get out of sync.