Represents a cross-column (row-level) check defined via the check macro.
check
The :function receives the entire row map and must return a truthy value for the check to pass. When it fails, an Error is produced with column: nil.
:function
Error
column: nil
@type t() :: %Scrutinex.Check{ function: (map() -> boolean()), message: String.t(), name: atom(), severity: :error | :warning }