Write a query to allow users to request a list of plant varieties.

Type
feature request

Problem or To-Do
Write a query to allow users to request a list of plant names. Query should:
- Accept the `id` of a plant type (plant type is general, i.e. "pepper")
- In turn call Trefle.io to get a list of all varieties of that plant type (i.e. "Habanero", "Serrano", "Thai", etc.)
- return results in graphql response, with variety { commonName, scientificName, id }

Start by locating the repository's existing GraphQL query and resolver entry points for plant types, then review how it calls Trefle.io. Confirm the external response fields and define the requested variety fields: commonName, scientificName, and id. Done means a plant type id returns its varieties in the GraphQL response, with the relevant query behavior verified.

Written by the indexing model from the issue text.