[graphiql] variables of type JSON not accepted

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Current Behavior

we have a vairable of the type JSON:

graphiql doesn't allow me to define any arbitrary JSON for this variable:

in other graphql webui it works fine. e.g. nitro of hotchocolate can handle this type.

### Expected Behavior

allow to assign any JSON value to this vairable

### Steps To Reproduce

see above

### Environment

* GraphiQL Version: 5.2.0
* OS: Windows 11
* Browser: Edge
* Bundler: Vite
* `react` Version: 19
* `graphql` Version:

### Anything else?

_No response_