FR: Separate hardlink/reflink directories per instance

[s0up4200]

Discussed in #1077

^{Originally posted by BaukeZwart January 4, 2026}
I use hardlinks for cross-seed organised by instance, for me that means I have my regular torrents in movies and the hardlinked in Movies (similar for my series instance).
I would prefer to have the hardlinks split per instance but in movies-xseed and series-xseed. As it's now we can use a custom category but not per instance.