fix: use color instead of fill for numeral styling

SVG foreign objects use CSS color property, not fill.
Changed numerals customStyle from fill to color for dark gray text.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/src/app/page.tsx

@@ -78,7 +78,7 @@ export default function HomePage() {
                   showNumbers={true}
                   customStyles={{
                     numerals: {
-                      fill: '#1f2937',
+                      color: '#1f2937',
                       fontWeight: 'bold',
                     },
                   }}