Initial commit: video effects processing system

Add S-expression based video effects pipeline with modular effect
definitions, constructs, and recipe files.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

effects/invert.py

@@ -0,0 +1,62 @@
+# /// script
+# requires-python = ">=3.10"
+# dependencies = ["numpy"]
+# ///
+"""
+@effect invert
+@version 1.0.0
+@author artdag
+
+@description
+Inverts the colors of each frame. Can be partial (blended with original)
+based on intensity parameter. Useful for beat-reactive flashing effects.
+
+@param intensity float
+  @range 0 100
+  @default 100
+  Intensity of the inversion effect (0 = original, 100 = fully inverted).
+  Bind to audio analysis for reactive effects.
+
+@example
+  (effect invert)
+
+@example
+  (effect invert :intensity 50)
+
+@example
+  ;; Beat-reactive inversion
+  (effect invert :intensity (bind bass :range [0 100] :transform sqrt))
+"""
+
+import numpy as np
+
+
+def process_frame(frame: np.ndarray, params: dict, state: dict) -> tuple:
+    """
+    Invert colors of a video frame.
+
+    Args:
+        frame: Input frame as numpy array (H, W, 3) RGB uint8
+        params: Effect parameters
+            - intensity: 0-100, how much to invert (default 100)
+        state: Persistent state dict (unused for this effect)
+
+    Returns:
+        Tuple of (processed_frame, new_state)
+    """
+    intensity = params.get("intensity", 100)
+
+    # Normalize intensity to 0-1
+    t = intensity / 100.0
+
+    if t <= 0:
+        return frame, state
+
+    if t >= 1:
+        return (255 - frame), state
+
+    # Partial inversion: blend between original and inverted
+    inverted = 255 - frame
+    result = (frame * (1 - t) + inverted * t).astype(np.uint8)
+
+    return result, state