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

chore: add prettier, changesets, and Spindle CI workflows master

- Add prettier for linting with lint/lint:fix scripts - Add @changesets/cli for version management and npm publishing - Add .tangled/workflows/ci.yaml (lint, typecheck, test on push/PR) - Add .tangled/workflows/publish.yaml (changeset version + publish on main) - Format codebase with prettier Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>