TranspilerOptions.replMode

Enable REPL mode transforms:

• Wraps top-level inputs that appear to be object literals (inputs starting with '{' without trailing ';') in parentheses
• Hoists all declarations as var for REPL persistence across vm.runInContext calls
• Wraps last expression in { proto: null, value: expr } for result capture
• Wraps code in sync/async IIFE to avoid parentheses around object literals