`vectorcraft-cli run/convert --scale` and the MCP export tool's `scale`
are raster pixels per point, but they were passed to every export, and
DXF reads `scale` as drawing units per unit: a 2x PNG next to a DXF
doubled the drawing and left it unitless ($INSUNITS 0). They now go
only to raster formats. DXF's own scale stays reachable through the
format options.