fix(js/ai): fixed GenerateStreamResponse output typing

[pavelgj]

No description provided.

[mbleigh]

1. I think the stream type needs to be a separate generic (in array format, stream chunks are z.infer<O>[] for example)
2. I'd prefer that the output response be entirely unaware of Zod -- it should be perhaps GenerateStreamResponse<O = unknown, S = Partial<O>>. Use z.infer when declaring the type from somewhere that already has Zod types.

[mbleigh]

1. I think the stream type needs to be a separate generic (in array format, stream chunks are z.infer<O>[] for example)
2. I'd prefer that the output response be entirely unaware of Zod -- it should be perhaps GenerateStreamResponse<O = unknown, S = Partial<O>>. Use z.infer when declaring the type from somewhere that already has Zod types.

Thinking on it more, I think it is actually always a partial of the output schema...you might be able to get away with:

O extends any[] ? Partial<O[number]>[] : Partial<O>