Type inference from serverValidate is misleading

Describe the bug

The type of the response from serverValidate (from a createServerValidate) in the example next server actions app has the age field as number, but if you access age at runtime it will be a string.

Your minimal, reproducible example

https://stackblitz.com/github/tanstack/form/tree/main/examples/react/next-server-actions?embed=1&theme=light&preset=node&file=src/index.tsx

Steps to reproduce

1. Open stackblitz
2. Check the type that ts expects for validatedData:

3. See at runtime that printed age is actually a string:

Expected behavior

I'd expect that the type of validatedData should be remain a FormData since it doesn't actually parse the fields into their typescript types.

Another option could be that all the fields of validatedData are strings?

How often does this bug happen?

None

Screenshots or Videos

No response

Platform

macOS
chrome 135

TanStack Form adapter

None

TanStack Form version

1.6.3

TypeScript version

5.8.2

Additional context

No response

Start with src/index.tsx in the linked next-server-actions StackBlitz example and trace createServerValidate through the serverValidate response type. Compare the declared validatedData type with the runtime age value. Done means the inferred type accurately reflects the returned data, with the expected representation for fields such as age made explicit.