Preserve bounds in reserved tool schemas (#40719)

## Why

Reserved tool parameter constraints must survive schema parsing so the model receives the declared limits.

## What changed

- Preserve `minimum` and `maximum` as exact JSON numbers.
- Preserve `maxLength` and infer a string schema when it is the only type hint.

## Testing

- Cover bounded integer, number, and string schemas through both parsing paths.
- Verify history and notes tools retain their constraints in app-server model requests.

GitOrigin-RevId: 4cc89722b5b226d595b57232ec3b8e825863faf3