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>

templates/standard-effects.sexp

@@ -0,0 +1,22 @@
+;; Standard Effects Bundle
+;;
+;; Loads commonly-used video effects.
+;; Include after primitives are loaded.
+;;
+;; Effects provided:
+;;   - rotate: rotation by angle
+;;   - zoom: scale in/out
+;;   - blend: alpha blend two frames
+;;   - ripple: water ripple distortion
+;;   - invert: color inversion
+;;   - hue_shift: hue rotation
+;;
+;; Usage:
+;;   (include :path "../templates/standard-effects.sexp")
+
+(effect rotate :path "../sexp_effects/effects/rotate.sexp")
+(effect zoom :path "../sexp_effects/effects/zoom.sexp")
+(effect blend :path "../sexp_effects/effects/blend.sexp")
+(effect ripple :path "../sexp_effects/effects/ripple.sexp")
+(effect invert :path "../sexp_effects/effects/invert.sexp")
+(effect hue_shift :path "../sexp_effects/effects/hue_shift.sexp")