Meter units in STEP export

[AdrianKriger]

Description:
When exporting a model where coordinates and heights are already in meters (e.g., from a UTM-projected GeoDataFrame), the resulting STEP file header defaults to SI_UNIT(.MILLI.,.METRE.). Like so:
... ... #9640 = ( LENGTH_UNIT() NAMED_UNIT(*) SI_UNIT(.MILLI.,.METRE.) ); ...
This causes downstream simulation tools to misinterpret the scale.

I have tried using showcase.save("file.step") and cq.exporters.export(shape, "file.step"), but the .MILLI. tag persists despite the raw numerical values being correct for a meter-based model.

Question:
What is the recommended way in CadQuery to explicitly set the LENGTH_UNIT to METRE in the STEP header without manually scaling all geometry points? Is there a global OCP/Interface_Static flag that is compatible with Assembly.save()?

[jmwright]

Related issues:

#1449

#1829