Add streaming video compositor with sexp interpreter

- New streaming/ module for real-time video processing:
  - compositor.py: Main streaming compositor with cycle-crossfade
  - sexp_executor.py: Executes compiled sexp recipes in real-time
  - sexp_interp.py: Full S-expression interpreter for SLICE_ON Lambda
  - recipe_adapter.py: Bridges recipes to streaming compositor
  - sources.py: Video source with ffmpeg streaming
  - audio.py: Real-time audio analysis (energy, beats)
  - output.py: Preview (mpv) and file output with audio muxing

- New templates/:
  - cycle-crossfade.sexp: Smooth zoom-based video cycling
  - process-pair.sexp: Dual-clip processing with effects

- Key features:
  - Videos cycle in input-videos order (not definition order)
  - Cumulative whole-spin rotation
  - Zero-weight sources skip processing
  - Live audio-reactive effects

- New effects: blend_multi for weighted layer compositing
- Updated primitives and interpreter for streaming compatibility

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

sexp_effects/primitive_libs/geometry.py

@@ -100,6 +100,24 @@ def prim_affine(img, src_pts, dst_pts):
     return cv2.warpAffine(img, M, (w, h))
 
 
+def _get_legacy_geometry_primitives():
+    """Import geometry primitives from legacy primitives module."""
+    from sexp_effects.primitives import (
+        prim_coords_x,
+        prim_coords_y,
+        prim_ripple_displace,
+        prim_fisheye_displace,
+        prim_kaleidoscope_displace,
+    )
+    return {
+        'coords-x': prim_coords_x,
+        'coords-y': prim_coords_y,
+        'ripple-displace': prim_ripple_displace,
+        'fisheye-displace': prim_fisheye_displace,
+        'kaleidoscope-displace': prim_kaleidoscope_displace,
+    }
+
+
 PRIMITIVES = {
     # Basic transforms
     'translate': prim_translate,
@@ -119,4 +137,7 @@ PRIMITIVES = {
     # Advanced transforms
     'perspective': prim_perspective,
     'affine': prim_affine,
+
+    # Displace / coordinate ops (from legacy primitives)
+    **_get_legacy_geometry_primitives(),
 }