Allow redirecting project-level settings writes to user-level settings

Feature request

When Claude Code persists permission approvals and other settings, it writes to .claude/settings.local.json in the project directory. There's no way to redirect these writes to ~/.claude/settings.json instead.

Use case

When working with multiple clones of the same repository (e.g. for concurrent Claude Code sessions), each clone gets its own .claude/settings.local.json. This means permissions and settings must be re-approved in every clone, and there's no way to centralize them.

Proposed solution

A setting or flag to write runtime settings (permission approvals, etc.) to ~/.claude/settings.json instead of the project-level .claude/settings.local.json.

These writes need to be safe for multiple concurrent sessions.