Backend: Expose agent versions in GraphQL

About

We want to expose agent versions in GraphQL.

Proposal

Because agent versions are part of a generic ItemVersion model, but do have a specific schema, we will need to use GraphQL interfaces to allow the frontend to select their properties:

{
  aiCatalogItems {
    nodes {
      name
      versions(first: 1) {
        nodes {
          id
      	  ...on AiCatalogAgentVersion {
      	    privileges
            userPrompt
            systemPrompt
      	  }
        }
      }
    }
  }
}

In this iteration the versions will not have any special filtering arguments.

In future, we could filter by a specific version numbers, or other states.

We could also in future add a version singular field that can be passed a version number or other state to return a single version, perhaps also a latestVersion field etc.