feat(v2): add multiple extra features from the pdf slides

backend/processing/tasks.py

@@ -48,6 +48,8 @@ def cleanup_expired_sessions():
     for session in expired:
         delete_relative_file(session.original_image)
         delete_relative_file(session.processed_image)
+        for state in session.states.all():
+            delete_relative_file(state.image)
     expired.delete()
 
     old_jobs = ProcessingJob.objects.filter(created_at__lt=timezone.now() - timezone.timedelta(hours=24))