feat(03-02): implement animation library — 7 types with registry and factory

- AnimationBase ABC with render(t, led_count) and from_params() contract
- SolidColorAnimation: time-independent uniform fill
- ChaseAnimation: moving lit segment with forward/reverse support
- PulseAnimation: sine-wave breathing effect (speed maps to period)
- RainbowAnimation: HSV hue cycle across strip via colorsys.hsv_to_rgb
- StrobeAnimation: on/off flashing at 1-20 Hz with configurable duty cycle
- ColorWipeAnimation: progressive fill from start or end
- FireAnimation: Fire2012 algorithm with cooling/sparking/heat-to-color mapping
- ANIMATION_REGISTRY + create_animation() factory function
- All 24 tests passing

lightsync/animations/chase.py

@@ -0,0 +1,58 @@
+"""Chase animation — a lit segment moves along the strip."""
+from lightsync.animations.base import AnimationBase
+
+
+class ChaseAnimation(AnimationBase):
+    """Moving lit segment(s) chasing along the strip.
+
+    At speed=1.0, the segment moves at 60 pixels/second.
+    Pattern repeats every (size + spacing) pixels.
+    """
+
+    def __init__(
+        self,
+        color: tuple[int, int, int] = (255, 255, 255),
+        bg_color: tuple[int, int, int] = (0, 0, 0),
+        speed: float = 0.5,
+        size: int = 3,
+        spacing: int = 7,
+        reverse: bool = False,
+        white: int = 0,
+    ) -> None:
+        self.color = tuple(color)  # type: ignore[arg-type]
+        self.bg_color = tuple(bg_color)  # type: ignore[arg-type]
+        self.speed = speed
+        self.size = size
+        self.spacing = spacing
+        self.reverse = reverse
+        self.white = white
+
+    def render(self, t: float, led_count: int) -> list[tuple]:
+        period = self.size + self.spacing
+        offset = int(t * self.speed * 60)  # pixels/sec at speed=1.0 is 60
+
+        pixels = []
+        for i in range(led_count):
+            if self.reverse:
+                pos = (i + offset) % period
+            else:
+                pos = (i - offset) % period
+
+            if pos < self.size:
+                pixels.append(self.color)
+            else:
+                pixels.append(self.bg_color)
+
+        return pixels
+
+    @classmethod
+    def from_params(cls, params: dict) -> "ChaseAnimation":
+        return cls(
+            color=tuple(params.get("color", [255, 255, 255])),  # type: ignore[arg-type]
+            bg_color=tuple(params.get("bg_color", [0, 0, 0])),  # type: ignore[arg-type]
+            speed=params.get("speed", 0.5),
+            size=params.get("size", 3),
+            spacing=params.get("spacing", 7),
+            reverse=params.get("reverse", False),
+            white=params.get("white", 0),
+        )