PR: Yet another fitting material issue

### Problem Description

Pipe Fittings color is not respected if the geometry in the family is a swept profile along an arc, and the Export setup used is IFC4x3. There might be more categories affected, this is the only I've tested.
They will have generic grey color by default, and the only thing that can change this is the object styles level override. System material colors doesn't get applied, nor custom override by IfcSingleMaterialOverride. If the sweep in the family has a straight path the overrides are working.

Sample files: https://inexkft-my.sharepoint.com/:f:/g/personal/tamas_deri_in-ex_hu/EkiqlFYwl0ZMnFC_QUU-qFABKGXM2me4hK1UaoNsOFBf-A?e=ERIEyp

IFC4

IFC4.3

### Revit Version

2026.0.x

### IFC for Revit Addon Version

26.1.0

### Windows Version

11 24H2

Start by reproducing the issue with the linked sample files in Revit 2026.0.x using IFC for Revit 26.1.0, comparing IFC4 and IFC4x3 exports for swept pipe fittings along an arc. Done means system material colors and IfcSingleMaterialOverride colors are respected for the affected geometry, rather than falling back to generic grey.

Written by the indexing model from the issue text.