Switch to ESM publishing, major version bump to 2.0.0

[Copilot]

Converts the package from CommonJS to native ESM output, with a major version bump to signal the breaking change.

Core changes

• package.json: Add "type": "module", "exports" field with import/types conditions, "types" field; version → 2.0.0
• tsconfig.json: module + moduleResolution → NodeNext (generates proper ESM with explicit .js specifiers in output)

Import updates

• All relative imports in src/ and src/tests/ updated to use explicit .js extensions (required by NodeNext)
• fp-ts deep imports updated from fp-ts/lib/Either → fp-ts/Either etc. (NodeNext resolution requires subpath exports or directory packages; fp-ts provides fp-ts/Either/package.json shims)

Config file renames

With "type": "module", .js config files are interpreted as ESM. Renamed to .cjs:

• .mocharc.js → .mocharc.cjs
• .eslintrc.js → .eslintrc.cjs

Test runner

Replaced ts-node with tsx — ts-node's ESM loader is incompatible with the PnP + Node.js v20+ --import requirement. tsx works natively via node-option: ['import=tsx'] in mocharc.

Build output

// build/index.js — now proper ESM
export * from './apply.js';
export * from './codecTools/index.js';
// ...

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• ofcncog2cu-dsn.algolia.net
  • Triggering command: /opt/hostedtoolcache/node/24.14.1/x64/bin/node /opt/hostedtoolcache/node/24.14.1/x64/bin/node /home/REDACTED/work/type-utils/type-utils/.yarn/releases/yarn-4.12.0.cjs add --dev tsx (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)