fix: TypeScript definitions in package.json/exports

[koistya]

Fixes package.json/exports

• "types" - can be used by typing systems to resolve the typing file for the given export. This condition should always be included first.
• "default" - the generic fallback that always matches. Can be a CommonJS or ES module file. This condition should always come last.

Reference

• https://nodejs.org/api/packages.html

Ref #114

[kwhitley]

Thanks @koistya!