print_pdf, shared by Export PDF, File › Print and Separations Preview, takes main's two
changes to the inline export pipeline: rasterize_layered runs only for PDF/A-2b (other
standards keep hidden placed-PDF layers as optional content), and the report gets
GRAPHIC_LAYER_RENDERING_WARNING when the source document has graphic layer visibility
overrides and the writer did not report it. The Separations Preview command matches
craft_prepress::Conversion with a fallback arm, since the enum is non-exhaustive at
craft-libs e3b9e239.