## uv requires `[build-system]` for entry points

Without `[build-system]` in `pyproject.toml`, uv treats the project as "virtual" and skips `[project.scripts]` entry points. `uv run reolink-ctl` will fail with `ModuleNotFoundError`.

Always include:

```toml
[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"
```

This also makes `uv sync` install the package properly, so `PYTHONPATH=.` is not needed for tests.
