Add generic streaming interpreter with configurable sources/audio

- Add stream_sexp_generic.py: fully generic sexp interpreter
- Add streaming primitives for video sources and audio analysis
- Add config system for external sources and audio files
- Add templates for reusable scans and macros
- Fix video/audio stream mapping in file output
- Add dynamic source cycling based on sources array length
- Remove old Python effect files (migrated to sexp)
- Update sexp effects to use namespaced primitives

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sexp_effects/effects/vignette.sexp

@@ -1,12 +1,13 @@
 ;; Vignette effect - darkens corners
+(require-primitives "image")
 
 (define-effect vignette
   :params (
     (strength :type float :default 0.5 :range [0 1])
     (radius :type int :default 1 :range [0.5 2])
   )
-  (let* ((w (width frame))
-         (h (height frame))
+  (let* ((w (image:width frame))
+         (h (image:height frame))
          (cx (/ w 2))
          (cy (/ h 2))
          (max-dist (* (sqrt (+ (* cx cx) (* cy cy))) radius)))