Just stumbled upon https://github.com/YousefED/typescript-json-schema and thought I’d leave this here. 
By the way, I just had another look at JSON Schema linking/extending, and that’s actually very straight-forward, just using $id URLs (or JSON pointers) and $ref. So I believe the details are mostly a question of tooling we set up around whatever registry scheme we come up with. For the JSON-LD data itself, and the client/module implementation of e.g. fetching (or storing) related documents, I’m not so sure.