Allow developers to define ComponentApis using raw JSON schemas rather than Zod objects

Some developers want to define a `ComponentApi` (and a `ComponentImplementation`) based on a JSON schema that they already maintain in a format other than Zod, e.g. a plain JSON schema object, or a TS interface etc.

Currently, `ComponentApi` exposes a Zod object as the schema, so this isn't really possible without Zod.

We would ideally have a story for this.

Options:

1. Migrate to Zod 4 which has `z.fromJSONSchema()` - https://zod.dev/json-schema
2. Tell developers to use https://www.npmjs.com/package/json-schema-to-zod or similar
3. Migrate our underlying logic to use raw JSON schemas instead of Zod