PR: Qto_CoveringBaseQuantities.Width exports incorrect

### Problem Description

The Default Thickness is 80 mm:

That should export to Qto_CoveringBaseQuantities.Width
Somehow it becomes 5:

Walls have Width, that exports correctly.
Ceilings and Floors have Default Thickness and it's exported incorrect.

Only when I add Width as a parameter it works but then I need to add the thickness manually.

IFC 4x3 Reference view from Revit 2026

### Revit Version

2026.4.x

### IFC for Revit Addon Version

26.4.1

### Windows Version

11 25H2

Start by reproducing the IFC 4x3 Reference View export from Revit 2026 using a ceiling or floor with Default Thickness set to 80 mm, then inspect the covering quantity export path for Qto_CoveringBaseQuantities.Width. Compare it with wall Width export behavior; done means ceilings and floors export Width as 80 mm rather than 5 without requiring a manually added Width parameter.

Written by the indexing model from the issue text.