Add optional dependencies for development and update .gitignore

- Added `.DS_Store` to `.gitignore` to prevent macOS system files from being tracked.
- Introduced optional development dependencies in `pyproject.toml`, including `pytest` and `responses`, to facilitate testing and development.
- Updated `uv.lock` with new package dependencies and versions for improved compatibility and functionality.
- Created new test files `conftest.py` and `test_view.py` to establish testing fixtures and implement unit tests for the `ModelView` class.

tests/conftest.py

@@ -0,0 +1,8 @@
+from pathlib import Path
+
+FIXTURES = Path(__file__).parent / "fixtures"
+
+
+def load(device: str, name: str = "config.conf") -> str:
+    """Read a device config fixture from tests/fixtures/<device>/<name>."""
+    return (FIXTURES / device / name).read_text(encoding="utf-8")