[Super app CMS] Define TypeScript types for Strapi responses and data types

[stevahnes]

My spidey sense tells me that there must be a way to get good TypeScript types based on the actual response shapes from Strapi. In #89, I manually redefined the Strapi model I configured in the Strapi UI + the extra stuff wrapping the model.

Investigate if there is a better way and (regardless of whether we find a better way), refactor the existing TypeScript types so that our use of Strapi is standardised.