🚀 [firebase_ai] Support for advanced Schema features with $ref and $def

[jacobsimionato]

There are some advanced JSON features like $ref and $def which allow for hierarchical structures etc.

They unlock a lot of powerful use cases, but they're not possible with Firebase AI logic right now. I think the two things we need are:

1. Support responseJsonSchema field in the API

Gemini can understand advanced schemas, but only when using the responseJsonSchema parameter rather than responseSchema (see GenerationConfig).

I believe Firebase AI Logic currently only supports responseSchema - see

flutterfire/packages/firebase_ai/firebase_ai/lib/src/api.dart

Line 1030 in db7e829

Map<String, Object?> toJson() => {

2. Support $ref and $def in Schema

Currently, Firebase's schema object does not support representing $ref and $def, so I think we'd need some support here.

See

flutterfire/packages/firebase_ai/firebase_ai/lib/src/schema.dart

Line 4 in db7e829

// you may not use this file except in compliance with the License.