fix: index.d.ts for plugins (#app → nuxt/app)

[Cheaterman]

📚 Description

I tried to manually type my plugin (I'm making a custom $fetch) because *.ts is linted by non-Nuxt-aware tslint/tsserver/etc instead of volar and therefore (I assume) can't simply infer types from the defineNuxtPlugin call.

I banged my head against the wall for a good while until I realized #app should actually read nuxt/app. :-)

[stackblitz]

Run & review this pull request in StackBlitz Codeflow.

[danielroe]

I think we would recommend instead to point tslint to your tsconfig.json - is there something that isn't working with that?

[danielroe]

I'm going to close this for now as it's intentionally #app but please do open an issue so we can discuss - maybe with a reproduction 🙏