Subs archive/repository

It'd be great if Bazarr could keep a separate folder as subs repository; each time a sub is added (auto or manual or brought in by Radarr or Sonarr), it'd also be copied to the repository, with it's original filename and some metadata like the purported match. If synced, instead of overwriting, it'd copy a new one to the repository, renaming to the release to which it was synced. If blacklisted, it'd get deleted from the repository.

That way, when Radarr or Sonarr upgrades a movie/episode and the subtitle gets deleted, Bazarr could search first (or also) in its own repository.

It becomes even more important if one sometimes go through the work of hunting down hard to find subs, syncing, checking, etc...