feat(01-01): create package structure, Pydantic models, and device abstractions

- pyproject.toml with FastAPI, uvicorn, Pydantic v2, aiofiles, structlog deps
- DeviceConfig Pydantic model with StripType, UUID, validation constraints
- ShowModel with AudioRef, TrackModel, CueModel, AnalysisBlock, schema_version=1
- BaseDevice ABC with encode_frame, encode_animation_cmd, bytes_per_pixel
- SK6812Device (4 bytes/pixel) and WS2801Device (3 bytes/pixel) implementations

lightsync/models/__init__.py

@@ -0,0 +1,4 @@
+from lightsync.models.device import DeviceConfig
+from lightsync.models.show import ShowModel
+
+__all__ = ["DeviceConfig", "ShowModel"]