build: Publish NPM package with type commonjs

[Danielku15]

Issues

Fixes #2045 #2044

Proposed changes

Node.js seems to have a bit a wierd behavior when it comes to loading modules. Despite the exports section defining (seemingly) the format and path for it, it behaves different.

Likely this started to become a problem with Node 22 which added support to load ESM files from CommonJS files:

The conditional export is only used to resolve the path to the file. But then if .js is used as extension, they load the file based on type in the parent package.json.

We have type: module as we mainly use ESM stuff in our own repo and a lot of tooling, and also node itself when executing scripts, rely on this. Again some tooling do not support extensions like .mts.

Using .cjs is also not fully correct as alphaTab itself is rather a UMD than a CJS only. The extension change would be a breaking one and could lead to problems when using this file in browser scenarios.

Putting this all together, our best choice is to rewrite the package.json before packing/publishing the NPM to mark publicly that .js files in this package are commonjs, but keeping things as ESM when working on this project.

Checklist

• I consent that this change becomes part of alphaTab under it's current or any future open source license
• Changes are implemented
• New tests were added

Further details

• This is a breaking change
• This change will require update of the documentation/website