Tracking/Notifications Add folders or tags to organize favorite mods

[maikjwad]

Problem:
Currently, users can only add mods to a single list of favorites. When someone tracks dozens or hundreds of mods, it becomes hard to navigate or organize them.

Suggestion:
Allow users to create custom folders or tags within their Favorites list. For example, one user might want to sort their favorites into folders like "Graphics Mods", "Gameplay Improvements", "Weapons", "Quests", etc.

Benefits:
- Makes it much easier to manage large mod libraries
- Helps users return to specific mods faster
- Encourages users to use the Favorite feature more often
- Opens the door for sharing organized favorite folders publicly (optional)

This would be especially useful for long-term Nexus Mods users who track mods for multiple games or playstyles.