Add `*(count)` method to both String and List classes in wren_core.wren, enabling eager repetition of string characters or list elements. The operator validates that count is a non-negative integer, aborting with a clear error message otherwise. For strings, concatenates the original string count times; for lists, builds a new list by adding all elements count times. Includes comprehensive test cases for normal, zero, and edge-case inputs, plus error tests for negative, non-integer, and non-numeric counts. Also refactors existing list plus tests to use inline expressions and adds a plus_not_iterable error test.
Bob Nystrom
b301e9f119