[BUG] XDG Path improvement

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Bump of #3833 since its closed prematurely.

What Should Happen?

.claude.json should follow state dir

Error Messages/Logs

Steps to Reproduce

open app

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

any

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_