PR: Rooms exported with wrong elevation with shared coordinates

### Problem Description

Revit 2025 & 2026 IFC Exporter 25.4.3
When we export a model with shared coordinates, the rooms are created high above the rest of the geometry. The offset is the height of the project elevation.
If we reset shared coordinates to zero, the rooms align properly. If we then set a now project elevation the problem returns.

### Revit Version

2025.0.x

### IFC for Revit Addon Version

26.1.0

### Windows Version

11 24H2

No source file, test, or entry point is named. Start by reproducing the export in Revit 2025 with shared coordinates and a nonzero project elevation, then compare the room elevation with the surrounding geometry; done means exported rooms align correctly without requiring shared coordinates to be reset.

Written by the indexing model from the issue text.