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/devices/base.py

@@ -0,0 +1,33 @@
+from abc import ABC, abstractmethod
+from lightsync.models.device import DeviceConfig
+
+
+class BaseDevice(ABC):
+    def __init__(self, config: DeviceConfig):
+        self.config = config
+
+    @property
+    def id(self):
+        return self.config.id
+
+    @property
+    def led_count(self) -> int:
+        return self.config.led_count
+
+    @abstractmethod
+    def encode_frame(self, pixels: list[tuple]) -> bytes:
+        """Encode a full pixel frame to UDP payload bytes.
+        pixels: list of (R, G, B) or (R, G, B, W) tuples.
+        """
+        ...
+
+    @abstractmethod
+    def encode_animation_cmd(self, animation: str, params: dict) -> bytes:
+        """Encode an animation+params command packet."""
+        ...
+
+    @property
+    @abstractmethod
+    def bytes_per_pixel(self) -> int:
+        """Number of bytes per LED in frame mode (3 for RGB, 4 for RGBW)."""
+        ...