Add a json schema builder

[dkbast]

Is your feature request related to a problem? Please describe.
I'm currently working with AI and want to give it a json schema so that it can pass back the values in the correct format

Describe the solution you'd like
A method on a freezed class that returns the schema, could also be a file which is generated when specifying it in the annotation - essentially I need a string describing the complete data schema with nesting etc pp - see https://docs.pydantic.dev/latest/api/base_model/#pydantic.BaseModel.model_dump_json for reference.

Describe alternatives you've considered
This would help in moving from Python to a Dart stack when building LLM tools / agents