Implement type validation after dining api gets openapi specs

[maybe-yiyi]

I would suggest using an actual type validation library derived from a generated open-api spec provided by the dining api (by using https://www.npmjs.com/package/openapi-typescript-validator, for instance), but we don't have an openapi spec just yet lmao. sorryyy

Originally posted by @cirex-web in #1 (comment)