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>

recipe-bound copy.sexp

@@ -0,0 +1,45 @@
+; Beat-synced video with full lambda control
+(recipe "bound-effects"
+  :version "1.0"
+  :encoding (:codec "libx264" :crf 22 :preset "fast" :audio-codec "aac" :fps 30)
+
+  (analyzer beats :path "../artdag-analyzers/beats/analyzer.py")
+  (analyzer bass :path "../artdag-analyzers/bass/analyzer.py")
+  (effect invert :path "../artdag-effects/invert/effect.py")
+  (effect sepia :path "sexp_effects/effects/sepia.sexp")
+
+  (construct slice-on :path "constructs/slice-on.sexp")
+
+
+  (def video-a (source :path "monday.webm" :description "Video A"))
+  (def video-b (source :path "new.webm" :description "Video B"))
+
+  (def video-c (source :path "ecstacy.mp4" :description "Video c"))
+
+  (def audio (-> (source :path "dizzy.mp3" :description "Audio input")
+                 (segment :start 0 :duration 10)))
+
+  (def beats-data (-> audio (analyze beats)))
+  (def bass-data (-> audio (analyze bass)))
+
+  ; Alternate sources and bind invert intensity to bass
+  ; slice-on produces a list of segments, then we explicitly concat with normalization
+  ; video-b always gets sepia effect applied
+  (def segments (slice-on beats-data
+                  :init 0
+                  :reducer (fn [acc i start end]
+                        (let [idx (mod acc 3)
+                              src (nth (list video-a video-b video-c) idx)
+                              base-effects (list {:effect invert :intensity (bind bass-data :range [0 100])})
+                              effects (if (= idx 1)
+                                        (concat base-effects (list {:effect sepia}))
+                                        base-effects)]
+                          {:source src
+                           :effects effects
+                           :acc (inc acc)}))))
+
+  ; Concatenate with resize normalization (fit to width, pad height)
+  (def synced-video (-> segments
+                        (sequence :resize-mode :fit :priority :width)))
+
+  (mux synced-video audio))