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/kaleidoscope.sexp

@@ -0,0 +1,21 @@
+;; Kaleidoscope effect - radial mirror segments
+;; Usage: python3 plan.py effects/kaleidoscope.sexp -p segments=6 -p rotation_speed=30 | python3 execute.py - -d . -o output.mp4
+;;
+;; Parameters:
+;;   segments: number of mirror segments (2 to 16, default: 6)
+;;   rotation_speed: rotation in degrees per second (0 to 180, default: 30)
+
+(recipe "kaleidoscope"
+  :version "1.0"
+  :encoding (:codec "libx264" :crf 20 :preset "medium" :audio-codec "aac" :fps 30)
+
+  (effect kaleidoscope :path "sexp_effects/effects/kaleidoscope.sexp")
+
+  ;; Default parameters (overridden by -p segments=N -p rotation_speed=N)
+  (def segments 6)
+  (def rotation_speed 30)
+
+  (def video (source :path "monday.webm"))
+  (def clip (-> video (segment :start 0 :duration 10)))
+  (def result (-> clip (effect kaleidoscope :segments segments :rotation_speed rotation_speed)))
+  result)