Fix GPU encoding black frames and improve debug logging

- Add CUDA sync before encoding to ensure RGB->NV12 kernel completes
- Add debug logging for frame data validation (sum check)
- Handle GPUFrame objects in GPUHLSOutput.write()
- Fix cv2.resize for CuPy arrays (use cupyx.scipy.ndimage.zoom)
- Fix fused pipeline parameter ordering (geometric first, color second)
- Add raindrop-style ripple with random position/freq/decay/amp
- Generate final VOD playlist with #EXT-X-ENDLIST

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

streaming/stream_sexp.py

@@ -1028,7 +1028,24 @@ class StreamInterpreter:
                 if result is not None:
                     import cv2
                     if result.shape[:2] != (h, w):
-                        result = cv2.resize(result, (w, h))
+                        # Handle CuPy arrays - cv2 can't resize them directly
+                        if hasattr(result, '__cuda_array_interface__'):
+                            # Use GPU resize via cupyx.scipy
+                            try:
+                                import cupy as cp
+                                from cupyx.scipy import ndimage as cpndimage
+                                curr_h, curr_w = result.shape[:2]
+                                zoom_y = h / curr_h
+                                zoom_x = w / curr_w
+                                if result.ndim == 3:
+                                    result = cpndimage.zoom(result, (zoom_y, zoom_x, 1), order=1)
+                                else:
+                                    result = cpndimage.zoom(result, (zoom_y, zoom_x), order=1)
+                            except ImportError:
+                                # Fallback to CPU resize
+                                result = cv2.resize(cp.asnumpy(result), (w, h))
+                        else:
+                            result = cv2.resize(result, (w, h))
                     out.write(result, self.ctx.t)
 
                 # Progress