Modernize codebase and update project config

[piekstra]

Summary

• Replace setup.py + pytest.ini with pyproject.toml (PEP 621)
• Remove Windows _ProactorBasePipeTransport hack from __init__.py — this was a workaround for an aiohttp bug fixed years ago
• Replace 14-branch if/elif device model dispatch in device_manager.py with a DEVICE_MODEL_MAP dictionary lookup
• CI now runs pip install -e . to install the package properly

Closes #94, closes #95