[Feature Request] Add option to conditionally skip loading ~/.claude/CLAUDE.md based on working directory

Bug Description
When working in a repository that contains its own CLAUDE.md at the root,
the user-level ~/.claude/CLAUDE.md is still loaded, causing duplicate
context (same content appears twice in the system prompt).

Requested feature: A setting in settings.json to specify directories
where the user-level CLAUDE.md should be skipped, e.g.:

{
"skipUserClaudeMdIn": ["~/HUB/repos/ghost"]
}

Or alternatively, a way to mark a repo's CLAUDE.md as "replaces user-level"
via frontmatter or similar mechanism.

Use case: I maintain a unified context repo that needs to work both locally
(via ~/.claude symlink) and on Claude Code Web (via GitHub clone). Currently,
any symlink approach causes duplication when working in the repo itself.

Related issues: #13288 (permission issues when running from ~/.claude)

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.0.76
• Feedback ID: 1d0c56bb-c9e7-463c-b14c-ce59ab03ad97

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/xxxx/.local/share/claude/versions/2.0.76 (expected in multi-process scenarios)\n    at XZR (/$bunfs/root/claude:2430:2165)\n    at fUA (/$bunfs/root/claude:2430:1885)\n    at processTicksAndRejections (native:7:39)","timestamp":"2025-12-25T06:16:51.024Z"}]