Update VideoEditor to set current display frame during rendering for improved motion tracking

This commit adds functionality to store the current display frame and update the current frame index during the rendering process. This enhancement supports better motion tracking by ensuring the correct frame is referenced, contributing to more accurate processing of video frames.

croppa/main.py

@@ -3836,6 +3836,10 @@ class VideoEditor:
                     if not ret:
                         break
 
+                    # Set current display frame for motion tracking during rendering
+                    self.current_display_frame = frame.copy()
+                    self.current_frame = start_frame + i
+                    
                     processed_frame = self._process_frame_for_render(frame, output_width, output_height, start_frame + i)
                     if processed_frame is not None:
                         if i == 0: