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/ripple.sexp

@@ -0,0 +1,21 @@
+;; Ripple effect - concentric wave distortion from center
+;; Usage: python3 plan.py effects/ripple.sexp -p amplitude=20 -p frequency=6 | python3 execute.py - -d . -o output.mp4
+;;
+;; Parameters:
+;;   amplitude: ripple strength in pixels (5 to 50, default: 20)
+;;   frequency: number of ripples (1 to 20, default: 6)
+
+(recipe "ripple"
+  :version "1.0"
+  :encoding (:codec "libx264" :crf 20 :preset "medium" :audio-codec "aac" :fps 30)
+
+  (effect ripple :path "sexp_effects/effects/ripple.sexp")
+
+  ;; Default parameters (overridden by -p amplitude=N -p frequency=N)
+  (def amplitude 20)
+  (def frequency 6)
+
+  (def video (source :path "monday.webm"))
+  (def clip (-> video (segment :start 0 :duration 10)))
+  (def result (-> clip (effect ripple :amplitude amplitude :frequency frequency)))
+  result)