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/wave.sexp

@@ -0,0 +1,21 @@
+;; Wave effect - sinusoidal distortion
+;; Usage: python3 plan.py effects/wave.sexp -p amplitude=30 -p wavelength=60 | python3 execute.py - -d . -o output.mp4
+;;
+;; Parameters:
+;;   amplitude: wave height in pixels (5 to 100, default: 30)
+;;   wavelength: wave period in pixels (20 to 200, default: 60)
+
+(recipe "wave"
+  :version "1.0"
+  :encoding (:codec "libx264" :crf 20 :preset "medium" :audio-codec "aac" :fps 30)
+
+  (effect wave :path "sexp_effects/effects/wave.sexp")
+
+  ;; Default parameters (overridden by -p amplitude=N -p wavelength=N)
+  (def amplitude 30)
+  (def wavelength 60)
+
+  (def video (source :path "monday.webm"))
+  (def clip (-> video (segment :start 0 :duration 10)))
+  (def result (-> clip (effect wave :amplitude amplitude :wavelength wavelength)))
+  result)