Remove the extraneous whitespace separating method names from their parameter lists
across all method definitions in the Set class (add, remove, contains, iterate,
iteratorValue, map, where) to conform to standard Wren formatting conventions.
Uncomment and implement the `|` (union) operator to return a new Set combining both lists, and the `&` (intersection) operator to return elements present in both sets. Refactor the `+` operator to delegate to `|` for consistency with bitwise semantics.
Implement a generic Set data structure backed by a list with automatic deduplication via cleanup method. Includes core set operations: element addition/removal, membership testing, cardinality, functional transformations (map/where), union via + operator, and set difference via - operator. Also provides iteration support through iterate/iteratorValue methods.
