Add typescript checks

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Currently we do not run typechecks, so we are not using the features of typescript.

Nuxt offers a guide https://nuxt.com/docs/guide/concepts/typescript but I could not get this to work (I enforced a type violation and it did not complain, so the type check is useless as described there?)

DoD

• Type checks fail if we introduce violations
• Type checks run in CI

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I really don't understand nuxt in this regard - following the official guide https://nuxt.com/docs/guide/concepts/typescript does not help as creating a type-bug within the code does not get explored, rendering the type-checking useless

there are multiple issues, some stating that the implicit auto-import creates issues, but even when turning this off and running the type-check does not yield any errors, while running the nuxt server yields in a runtime error :/