The PR showed one theme's badge and sticker sheets, which cannot show that the
filled treatments read on every palette. Each shipped theme and scheme now
gets its own sheet: both semantic families, three glyphs, as line glyphs,
stickers and badges, at 16 and 24 px, on the window and button surfaces the
contrast is measured against, with the disabled fallback under each family.
The generator lives in its own test file so the preview work does not have to
move the branches above it.
