Duplicate .claude/rules loading in worktrees nested inside .claude/

Summary

When using worktrees created inside .claude/worktrees/, rules from .claude/rules/ are loaded twice — once from the worktree's own copy and once from the parent repo's .claude/rules/ (discovered via ancestor directory traversal).

Steps to reproduce

1. Have a project with .claude/rules/ containing rule files
2. Enter a worktree (created at .claude/worktrees/<name>/)
3. Observe that rules are loaded twice:

Loaded ../../rules/pagination.md
Loaded ../../rules/security.md
Loaded ../../rules/viewsets.md
Loaded .claude/rules/pagination.md
Loaded .claude/rules/security.md
Loaded .claude/rules/viewsets.md

Expected behavior

Each rule file should be loaded only once. When operating inside a worktree, the rule discovery should deduplicate rules that resolve to the same file content/origin, or skip ancestor .claude/rules/ directories that belong to the parent repo.

Actual behavior

Rules are loaded twice because:

• The worktree is physically located at <repo>/.claude/worktrees/<name>/
• The worktree has its own .claude/rules/ (checked into git)
• Walking up the filesystem from the worktree also finds <repo>/.claude/rules/
• Both are loaded, resulting in duplicate context and wasted tokens

Impact

• Duplicate context consumes tokens unnecessarily (each rule file is sent twice)
• With many rule files, this compounds significantly

Suggested fix

During rule discovery, if the current working directory is a worktree nested inside another repo's .claude/, skip ancestor .claude/rules/ directories that belong to the parent repo.