Fix OpenCV contiguous array error in _save_blended_frames (#512) (#513)

Apply the same np.ascontiguousarray fix from #510 to _save_blended_frames,
which was also affected by OpenCV 4.12+ requiring C-contiguous arrays for
in-place drawing operations like cv2.putText.

Author: giswqs

samgeo/samgeo3.py

@@ -5030,6 +5030,7 @@ def _save_blended_frames(
             mask_3d = mask_combined[:, :, np.newaxis]
             blended = frame_np * (1 - mask_3d * alpha) + overlay * (mask_3d * alpha)
             blended = np.clip(blended, 0, 255).astype(np.uint8)
+            blended = np.ascontiguousarray(blended)
 
             # Draw labels using OpenCV
             for cx, cy, label, color in labels_to_draw: