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/flip.py

@@ -0,0 +1,64 @@
+# /// script
+# requires-python = ">=3.10"
+# dependencies = ["numpy"]
+# ///
+"""
+@effect flip
+@version 1.0.0
+@author artdag
+
+@description
+Flips the frame horizontally and/or vertically.
+Can be used for mirror effects or beat-triggered flips.
+
+@param horizontal bool
+  @default false
+  Flip horizontally (left-right mirror).
+
+@param vertical bool
+  @default false
+  Flip vertically (top-bottom mirror).
+
+@example
+  (effect flip :horizontal true)
+
+@example
+  (effect flip :vertical true)
+
+@example
+  (effect flip :horizontal true :vertical true)  ; 180 degree rotation
+"""
+
+import numpy as np
+
+
+def process_frame(frame: np.ndarray, params: dict, state: dict) -> tuple:
+    """
+    Flip a video frame horizontally and/or vertically.
+
+    Args:
+        frame: Input frame as numpy array (H, W, 3) RGB uint8
+        params: Effect parameters
+            - horizontal: flip left-right (default False)
+            - vertical: flip top-bottom (default False)
+        state: Persistent state dict (unused)
+
+    Returns:
+        Tuple of (processed_frame, new_state)
+    """
+    horizontal = params.get("horizontal", False)
+    vertical = params.get("vertical", False)
+
+    result = frame
+
+    if horizontal:
+        result = np.flip(result, axis=1)
+
+    if vertical:
+        result = np.flip(result, axis=0)
+
+    # Ensure contiguous array after flips
+    if horizontal or vertical:
+        result = np.ascontiguousarray(result)
+
+    return result, state