test: validate published package contract

[okyrychenko-dev]

Summary

Add automated validation for the package consumers actually install.

Changes

• add @arethetypeswrong/cli and publint
• add format-specific ESM and CommonJS declaration exports
• add a packed-artifact validation script covering:
  • published file contents
  • export targets
  • runtime and peer dependencies
  • required React peer metadata
  • sideEffects: false
  • "use client" preservation
  • ESM and CommonJS loading
  • NodeNext TypeScript consumers
• add a public API type-consumer fixture
• include validation scripts in lint and formatting checks
• run package:check in CI and through release:check
• update the pnpm lockfile

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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