fix(control): prevent duplicate save_video and unmask video module shadow

When a video script (animatediff, text2video, image2video, stablevideodiffusion)
runs via Control tab, both the script's save and control_run's end-of-run save
fired. The latter crashed silently because the local `video` cv2 capture name at
control_run:584 shadowed the modules.video import, so the duplicate was hidden
and the gallery video link never propagated.

- alias import as video_module to bypass the shadow
- p.video_saved marker set by each script
- control_run skips its end-of-run save when the marker is set

scripts/text2video.py

@@ -91,4 +91,5 @@ class ModelScopeScript(scripts_manager.Script):
 
         if video_type != 'None':
             video.save_video(p, filename=None, images=processed.images, video_type=video_type, duration=duration, loop=gif_loop, pad=mp4_pad, interpolate=mp4_interpolate)
+            p.video_saved = True
         return processed