[Feature] Background process to remove unused/orphaned metadata and media

[JDIacobbo]

Is your feature request related to a problem? Please describe. Yes, I recently cleared out a number of items from my library but it appear the metatdata/media files remain.

Describe the solution you'd like A background process to check for and remove any unused/orphaned metadata and media files. Would also be helpful to have the option to manually run the process.

Describe alternatives you've considered n/a.

Additional context n/a

[gantoine]

You'll be happy to know we'll be working on this right after 4.0 releases!