feat: publish esm-only package

[anajavi]

closes #72

• add type: "module" to package.json
• build only esm, commonjs was dropped

notes:

1. converted tests to vitest as jest+ts-jest was way too hard to make work with moduleResolution: nodenext
2. I had to bypass commit hooks as prettier@2 is too old to understand import attributes:

   import entities from "./html-entities.json" with { type: "json" };

   Separate PR for prettier upgrade chore: upgrade prettier to v3 #156
3. I added a couple of eslint rules to prevent type only imports pulling code along.
4. Removed ts-node as node can run ts files by itself

require(esm) from commonjs supported in node since:

• v20.19.0+
• v22.12.0+

I can add exports map to package.json if it is needed.

[anajavi]

As this is already a breaking change, might as well change the jsx transform on tsconfig to:

"jsx": "react-jsx"

mjml-react/tsconfig-base.json

Line 4 in 0d69185

"jsx": "react",

React 19 wants to use it:
https://react.dev/blog/2024/04/25/react-19-upgrade-guide#new-jsx-transform-is-now-required

The jsx transform is supported since react 16.14

Doing it now might prevent a breaking change in the future.

What do you think?

[anajavi]

@emmclaughlin do you think releasing ESM only package is the right way?