Expand $variants to accept an array of csv paths, concatenating their
rows. Detect a path by a .csv suffix on the first line instead of a
newline, so inline csv and paths are self-documenting and the rule
applies uniformly to single values and array elements.
Parse yaml/json/toml and markdown code blocks into packages, expanding
$variants via typed-csv and collecting parts, surfaces, and setups by
include patterns. Ships zod validation, a vitest config, and 16 tests.
hypercross