Use safeParse instead of parse for zod schemas to improve error reporting

[jds2501]

The error reporting on zod parsing failures right now reports "Invalid response schema," which made debugging some stagehand test failures difficult. We can improve error handling by using a pattern like this:

const result = schema.safeParse(data);

if (!result.success) {
// log or rethrow with detail
throw new MyCustomError(result.error.format());
}

const parsed = result.data;

This would allow you to get more explicit guidance on why Zod schema parsing failed - example:

{
name: { _errors: ['Required'] },
age: { _errors: ['Expected number, received string'] },
_errors: []
}

[kamath]

Thanks for the feedback!! We can certainly take this on, unless someone else wants to handle this :)

[CtrlAltGiri]

I'm happy to take this!

[CtrlAltGiri]

Have a first iteration here: #690

[CtrlAltGiri]

@kamath can you review this please?