Add 15 static overloads of IO.print in builtin/io.wren and src/wren_io.c, each delegating to a new private printList_ method that iterates over a list of objects. Update all benchmark and test files to use the new multi-argument syntax, removing explicit .toString calls and string concatenation. Add a comprehensive test/io/print.wren verifying single-argument return value, multi-argument null return, and concatenation of up to 16 arguments.
Refactor `finishBlock` in `wren_compiler.c` to detect single-expression bodies (no newline after `{`) and leave a value on the stack, enabling implicit returns for methods and functions. Add `finishBody` wrapper to handle constructor flag. Update all benchmark and test `.wren` files to remove explicit `return` keywords from getters and single-expression methods, relying on the new implicit return behavior. Remove old `return_null_if_brace.wren` test, add `newline_body.wren`, `newline_in_expression_block.wren`, and `no_newline_before_close.wren` tests for edge cases.
Rename the IO.write method to IO.print, which now prints without a trailing newline, and add a new IO.print method that appends a newline after output. Update all benchmark, example, and test files to use IO.print instead of IO.write. Additionally, implement Unicode escape sequence parsing in the compiler's string tokenizer, supporting \uXXXX and \u{...} syntax with proper UTF-8 encoding for code points up to U+10FFFF.
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
