Add geometry database (.rdbview) export to IfcViewerFull

Wire a new "Export Geometry Database" tool button in AddModelDialog,
adjacent to "Convert IFC File to Database", to produce a zipped
read-only artifact combining a lossy RDB (with IfcRepresentationItem
stripped) and a .ifcview geometry sidecar. Intended for cloud
coordination workflows where parametric geometry editing is not needed.

Pipeline changes to support this:

- document_serializer_context gains a `skip_supertypes` field; the
  rdb plugin forwards it to RocksDbSerializer so the same registry
  path produces full or lossy RDBs.

- Vertex quantization helpers (octEncodeNormal + quantizeVertex) move
  out of ViewportWindow.cpp into a shared header so the sidecar's
  byte layout stays identical regardless of whether it came from a
  GPU readback or a CPU pipeline.

- New HeadlessSidecarBuilder runs a GeometryStreamer on the calling
  thread, captures MeshChunk/InstanceChunk into a SidecarData on the
  CPU, then computes georef + packed elements + LODs and writes the
  .ifcview — no ViewportWindow or GL context required.

The Controller's export flow runs RDB conversion + sidecar build +
QZipWriter packaging on a background QThread, writing through
`<dest>.tmp` then renaming for atomic appearance in cloud-sync
folders. ifcviewer-full now links Qt6::CorePrivate for QZipWriter.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/serializers/document_rdb_plugin.cpp

@@ -31,7 +31,7 @@ boost::shared_ptr<Serializer> create_serializer(const ifcopenshell::serializers:
 	if (context.input_filename.empty()) {
 		throw ifcopenshell::exception("RocksDB document serializer requires an input filename");
 	}
-	return boost::make_shared<RocksDbSerializer>(context.input_filename, context.output_filename);
+	return boost::make_shared<RocksDbSerializer>(context.input_filename, context.output_filename, context.skip_supertypes);
 }
 
 }