feat(video): wire scripts and control to video_interpolate field

Set p.video_interpolate at run() entry so process_images_inner picks up
the helper. Save calls keep their existing kwargs; the sentinel guard
skips re-interpolation when the helper already ran.

- animatediff, text2video, image2video, stablevideodiffusion route
  mp4_interpolate into p.video_interpolate
- modules/control/run.py routes the request video_interpolate arg
- xyz_grid intentionally untouched: its end-of-axis save_video stitches
  the cell slideshow, not per-cell videos; a future video_interpolate
  axis would set p.video_interpolate per cell via axis_options

scripts/animatediff.py

@@ -248,6 +248,7 @@ class AnimateDiffScript(scripts_manager.Script):
         p.extra_generation_params['AnimateDiff'] = loaded_adapter
         p.do_not_save_grid = True
         p.ops.append('video')
+        p.video_interpolate = mp4_interpolate
         p.task_args['generator'] = None
         p.task_args['num_frames'] = frames
         p.task_args['num_inference_steps'] = p.steps