File G4OCCT_STEPAssembly.cc: Phase 2: return per-solid placement data from the OCCT-side TU and populate the dd4hep::Assembly with TGeo placeholder volumes so that DD4hep and visualisation tools can see the constituent geometry.
File G4OCCT_STEPSolid.cc: Phase 2: replace the TessellatedSolid with a proper TGeo↔G4OCCTSolid bridge so that Geant4 navigation uses the exact OCCT BRep geometry for all geometric queries (SurfaceNormal, DistanceToIn, etc.).