Add React 19 support

[cminn10]

Hey team, I'm using jotai-devtools@0.13.0 with React 19.2.4 and getting peer dependency warnings during installation:

warn: incorrect peer dependency "react@19.2.4"
warn: incorrect peer dependency "@types/react@19.2.10"

Looks like the issue is coming from the react-json-tree dependency, which currently only supports React up to 18.x.

Everything works fine at runtime (React 19 is backward compatible), but it would be great to officially support React 19 and eliminate these warnings.

Thanks for the awesome devtools! 🙌