[FEAT] Support Valibot as well

Is your feature request related to a problem? Please describe.

I already have a backend system that uses valibot, and I would like to use volt agent with that existing setup. However, volt agent currently only supports zod, which means we cannot use our existing valibot schemas. As a result, I have to rewrite schemas implemented in valibot using zod. To avoid this extra work, I would like to add support for valibot as well.

Describe alternatives you've considered

No response

Additional context

No response

Describe the thing to improve

Enable the use of Valibot for schema definitions.