CLAUDE.md loads twice on the nested_traversal path when two paths reach the same file

Claude Code loads one `CLAUDE.md` file twice when two different path spellings reach it and one of them sits below the working directory. The session-start loader resolves symlinks and dedupes correctly. The `nested_traversal` loader compares literal path strings, so it loads a file the session already holds.

https://github.com/anthropics/claude-code/issues/73335 covers the session-start half (fixed). This issue covers the nested path.

## Environment

- Claude Code 2.1.272
- macOS, Darwin 27.0.0, arm64

## Steps to reproduce

1. Run `mkdir -p /tmp/repro/sub && printf 'hi\n' > /tmp/repro/sub/note.txt`.
2. Write about 27 KB of filler text to `/tmp/repro/sub/CLAUDE.md`. Include the token `UNIQUEMARKER-Q7X` one time.
3. Run `ln -s /tmp/repro/sub/CLAUDE.md ~/.claude/CLAUDE.md`.
4. Change to `/tmp/repro`.
5. Run `claude -p "Use the Read tool on ./sub/note.txt, then reply with only the number of copies of UNIQUEMARKER-Q7X in your context." --model sonnet --output-format json`.

## Result

The model answers `2`. It must answer `1`.

An `InstructionsLoaded` hook records both loads:

```
User session_start ~/.claude/CLAUDE.md
Project nested_traversal /private/tmp/repro/sub/CLAUDE.md
```

The prompt prefix grows from 43,064 tokens before the Read to 56,093 after it. One copy of the fixture measures 12,807 tokens, so the session pays for the file twice.

## Controls

- The same file at the working-directory root loads one time, and the model answers `1`.
- Without a Read inside `sub/`, only the user entry loads.
- A project-root `CLAUDE.md` symlinked to `sub/CLAUDE.md` also loads twice, and costs 12,942 extra tokens.
- A real root `CLAUDE.md` whose `sub/CLAUDE.md` symlinks back to it also loads twice, and costs 12,937 extra tokens.

The last two controls show the defect is not specific to user memory. A symlink on either side defeats the nested loader.