I don’t actually know. I mean, I imagine there is, yes. But I don’t know what it looks like. I imagine this is one for @ErikSchierboom when he’s back, or @SleeplessByte might know as I think he has Exercism-hosted packages in NPM too.
@lpil can you post your NPM username here? I can add you to the org (I think).
Since I don’t know how much you know about the npm eco-system I will assume you know almost nothing - even though you probably just need the NPM access - so it may benefit future readers.
npm publish --access public
# Or for yarn
yarn npm publish --access public
You seem to be using NPM (given package-lock.json), so the first one is applicable. It seems that you need to run build before publishing. Thus, for npm, you probably want (which you already have):
// package.json
"prepare": "npm run build"
You also already indicate the build output in the "files" array, which is the right thing to do.
TL;DR, tell me your NPM username and you can self-publish this.