Add hide empty mod categories setting

[daymi-el]

Summary

• add a Settings Panel checkbox for hiding empty CustomWheel categories
• persist hide_empty_categories through the existing backend settings flow
• hide empty non-Skins CustomWheel rows on wheel open while always keeping Skins visible
• refresh wheel settings on each open so toggling the setting applies on the next open

Verification

• redo the steps from the video

[daymi-el]

feature preview

rose_hide_empty_mod_categories_video.mp4

[Alban1911]

Ok very good addition, this should defo be a default setting, I'll look into it asap ty