Add multi-panel Pico UDP firmware and Python LED control.

Pico panels get static IPs on 10.1.1.10–14 with per-panel LED counts, Makefile deploy targets, and Python examples for animations, sync tests, and direct Pi SPI control.

Co-authored-by: Cursor <cursoragent@cursor.com>

leds/backends/pio.py

@@ -0,0 +1,58 @@
+"""WS2812 via Pi 5 kernel ws2812-pio driver (/dev/ledsN)."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+
+class PioBackend:
+    def __init__(self, led_count: int, *, device: str = "/dev/leds0") -> None:
+        self._led_count = led_count
+        self._device = device
+        self._path = Path(device)
+        if not self._path.exists():
+            raise FileNotFoundError(
+                f"{device} not found — enable ws2812-pio in /boot/firmware/config.txt "
+                "and reboot. Run: pipenv run python examples/setup_pi5_leds.py"
+            )
+
+    @property
+    def led_count(self) -> int:
+        return self._led_count
+
+    @property
+    def device(self) -> str:
+        return self._device
+
+    def write_grb(self, grb_bytes: bytes) -> None:
+        if len(grb_bytes) != self._led_count * 3:
+            raise ValueError(
+                f"expected {self._led_count * 3} bytes, got {len(grb_bytes)}"
+            )
+
+        # Kernel driver expects RGBW uint32 little-endian per pixel (W=0 for RGB).
+        frame = bytearray(self._led_count * 4)
+        for i in range(self._led_count):
+            base = i * 3
+            g, r, b = grb_bytes[base], grb_bytes[base + 1], grb_bytes[base + 2]
+            offset = i * 4
+            frame[offset] = r
+            frame[offset + 1] = g
+            frame[offset + 2] = b
+            frame[offset + 3] = 0
+
+        with open(self._path, "wb") as dev:
+            dev.write(frame)
+
+    def clear(self) -> None:
+        with open(self._path, "wb") as dev:
+            dev.write(b"\x00" * (self._led_count * 4))
+
+    def close(self) -> None:
+        self.clear()
+
+    def __enter__(self) -> PioBackend:
+        return self
+
+    def __exit__(self, *_exc) -> None:
+        self.close()