Replace the global `io` singleton object with a static `IO` class, moving the `write` native from the instance to the metaclass. Update all benchmark, example, and test files to use `IO.write()` instead of `io.write()`.
- Add TOKEN_LINE matching after list elements in compiler to allow newlines before commas or closing brackets
- Add tests for list newline handling, EOF after comma/element, and class name inside body
- Remove resolved TODOs for default constructors, inherited fields, metaclass is checks, zero comparison, and bitwise not behavior
