[Feature]: Ability to add a custom category and group/combine categories.

[PeTeFIN]

Describe the feature

Would be great if i could add my own Categories and add existing dynamic (?) categories under that one.

Describe the implementation

So, adding custom categories is pretty clear, but i would like to have ability to add category like JEWELRY, and then put the category RING, NECK, TRINKET to go under that one. So kinda of grouping of multiple categories.

Or i like to have my speedrun related items in one group, it has gear and consumables mixed in there.