Add N-Queens puzzle

Create an N-Queens puzzle where users can place queens on an n x n chessboard. The size of the board can be adjusted using a slider. A timer can be started before placing any queens. Clicking a square places a queen, and clicking a queen removes it. Attacked squares are visually indicated.

src/pages/NQueensPuzzlePage.tsx

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+import React from 'react';
+import NQueensPuzzle from '@/components/NQueensPuzzle';
+
+const NQueensPuzzlePage = () => {
+  return (
+    <div className="min-h-screen bg-background">
+      <NQueensPuzzle showSocialShare={true} />
+    </div>
+  );
+};
+
+export default NQueensPuzzlePage;