fix: add missing scaleX and scaleY number conversions

The scaleX and scaleY variables were still needed for region bounding
box calculations later in the code. Added .toNumber() conversions from
the Big.js versions to regular numbers for these calculations.

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

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

apps/web/src/arcade-games/know-your-world/components/MapRenderer.tsx

@@ -1038,6 +1038,8 @@ export function MapRenderer({
       // Convert to numbers for use in calculations
       const cursorSvgX = cursorSvgXBig.toNumber()
       const cursorSvgY = cursorSvgYBig.toNumber()
+      const scaleX = scaleXBig.toNumber()
+      const scaleY = scaleYBig.toNumber()
 
       // Zoom search logging disabled for performance