fix: remove mispositioned background rect from magnifier SVG

Remove the background rect element from the magnifier SVG that was
appearing incorrectly positioned to the left. The magnifier container
already has its own background styling, so the SVG rect is unnecessary.

🤖 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

@@ -1924,9 +1924,6 @@ export function MapRenderer({
               height: '100%',
             }}
           >
-            {/* Background */}
-            <rect x="0" y="0" width="100%" height="100%" fill={isDark ? '#111827' : '#f3f4f6'} />
-
             {/* Render all regions in magnified view */}
             {mapData.regions.map((region) => {
               const isFound = regionsFound.includes(region.id)