List directory contents as a tree structure.

Use this tool to:
- Understand project layout and structure
- Find files and subdirectories
- Navigate unfamiliar codebases

The output shows directories with trailing "/" and uses tree-style formatting.

## Parameters

- `path`: Directory to list (defaults to working directory)
- `depth`: Maximum depth to traverse (default: 3)
- `limit`: Maximum entries to show (default: 100)

## Example Output

```
/home/user/project/
├── src/
│   ├── main.py
│   ├── utils/
│   │   ├── helpers.py
│   │   └── config.py
│   └── tests/
│       └── test_main.py
├── README.md
└── pyproject.toml
```

Common directories like node_modules, .git, __pycache__, .venv are automatically ignored.
