fix: remove duplicate containerRect declaration

TypeScript error: containerRect was declared twice in the same scope.
The variable is already declared at the top of handleMouseMove, no
need to redeclare it when calculating magnifier position.

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

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

@@ -910,7 +910,7 @@ export function MapRenderer({
       }
 
       // Calculate magnifier position (opposite corner from cursor)
-      const containerRect = containerRef.current.getBoundingClientRect()
+      // containerRect already declared at top of function
       const magnifierWidth = containerRect.width * 0.5
       const magnifierHeight = magnifierWidth / 2
       const isLeftHalf = cursorX < containerRect.width / 2