[enhancement]: Board Groups/Folders

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Contact Details

_No response_

### What should this feature add?

Being able to put Boards in "Folders" for better organization would be very appreciated.

For instance, if you want to have a Folder for video game characters, cartoons, anime, genders, etc.

Right now we have an extremely long list to scroll down, and even if we use tags like "male" to sort the images, we then can't use the opposite such as "female".

Just a small gripe with the Board system. Otherwise I really enjoy using Invoke. Thanks for the work you guys have done. :D

### Alternatives

_No response_

### Additional Content

_No response_

Start by locating the Board system in the WebUI and reviewing how boards are currently listed and organized. The issue does not identify files, entry points, or settled behavior; the work would be complete when a defined folder system lets users organize and navigate boards without relying on an unbounded list.

Written by the indexing model from the issue text.