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/components/InteractiveIndex.tsx

@@ -180,6 +180,15 @@ const allInteractives: Interactive[] = [
     path: '/puzzles/sikinia-parliament',
     theme: 'Puzzles',
     dateAdded: '2024-12-22'
+  },
+  {
+    id: 'n-queens',
+    title: 'N-Queens Puzzle',
+    description: 'Place as many queens as possible on an n×n chessboard so that no two queens attack each other.',
+    tags: ['logic', 'chess', 'placement', 'classic'],
+    path: '/puzzles/n-queens',
+    theme: 'Puzzles',
+    dateAdded: '2024-12-22'
   }
 ];