Offload functions to worker threads with shared memory primitives for Node.js.

feat: auto-transfer return values from workers master

Worker return values that are transferable (ArrayBuffer, TypedArray, streams, etc.) are automatically added to the postMessage transfer list. No explicit transfer() wrapping needed on the return path since the worker is done with the value. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>