Support seed for chat completions in render in ai/rsc

[roguesherlock]

Feature Description

Hey I think it'd be nice add an option for seed to render function in ai/rsc. Let me know if you want me to create a pr for this. It should be quick one

https://platform.openai.com/docs/guides/text-generation/reproducible-outputs

Use Case

Being able to reproduce outputs for debugging purposes

Additional context

No response