Prefabs reference the TMP SDF asset made from a font, not the .ttf, so matching the
font file guid alone could never fail. The unreferenced-font check now follows the
font guid and the guid of every Assets/Fonts file that references a guid already
followed (the font's own SDF asset, any SDF asset listing it as a fallback); a file
outside Assets/Fonts naming any of them is a use.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>