badge/build.png draws the same two-part pill as badge/build.svg, for readers that cannot decode SVG. iOS is the case that forced it: UIImage decodes SVG only from an asset catalog, so a native README view has no way to render the SVG badge.
Drawn at 2x, since a raster badge has no other way to stay sharp and carries no channel to declare its own scale. Text is Go Regular, the only TTF in the module graph, measured against the real face rather than the Verdana approximation the SVG needs because it ships no metrics.
Adds golang.org/x/image for the rasterizer — pure Go, and the fifth golang.org/x/* dependency.
buildBadge and buildBadgePNG share repo resolution and build lookup through badgeState, so private repositories still 404 on both paths.