INQ: How to export Revit Category as Revit user defined property set?

### Inquiry description

If I export using `Export Revit property sets` then I can see the `Category` property. However I can't figure out how to export it using a user defined property sets config file. Here is what I've tried:

```
PropertySet: LL_Revit I IfcElement
Family Label # works
Family and Type Label # works
Type Label # works
Type Id Label # works
Category Label # nothing
Revit Category Label # nothing
Category Id Label # nothing
Category Name Label # nothing
```

### Revit Version

2026.4.x

### IFC for Revit Addon Version

26.4.1

### Windows Version

11 25H2

No source files, tests, or entry points are named. Reproduce the built-in Revit property-set export and the LL_Revit user-defined configuration using the listed Revit and addon versions; done means Category exports through the user-defined property set or the supported configuration limitation is documented.

Written by the indexing model from the issue text.