Clean up schemas and type definitions

[Lms24]

Seems like we have three type/schema definitions at the moment:

• /schemas with JSON schema
• /docs/src/content.config.ts for the Astro docs using astro/zod for validation
• /scripts/types.ts for the code generation script

It would be nice if we could unify these or at least keep them better in sync. Definitely opens up room for divergence at the moment.
If we could use zod for code generation we can likely eliminate some type casts.

h/t @nsdeschenes for raising!

[linear-code]

CON-99