[Feature Request] Docker image + batch processing

Hi and thanks for this amazing project.

I'm hosting (like many) an instance of Plex/Emby/Jellyfin in a containerised environment and I think this project would be a godsend for such scenarios.

What I'm suggesting with this Issue is the possibility of making ffusbsync available as a container image, able to run as a deamon and operate continuously on a pre-defined media library (path passed as an ENV variable when container is started maybe?).

Structure of these media library (regardless of the media service used) looks like this:

• LIbrary
  • Film_A
    • Film_A.mkv
    • Film_A.srt
  • Film_B
    • Film_B.mkv
    • Film_B.srt

What do you think about it? Thanks!