fix(rithmomachia): correct board dimensions to 16x8 and restore original layout values

The board was incorrectly showing as 8x8 instead of the correct 16x8 dimensions
for Rithmomachia. This also fixes gap (5→2) and padding (20→10) values that
were incorrectly changed.

- Set BOARD_COLUMNS to 16 (was 8)
- Update COLUMN_LABELS to A-P (was A-H)
- Restore gap to 2 (was changed to 5)
- Restore padding to 10 (was changed to 20)

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

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

apps/web/src/arcade-games/rithmomachia/constants/board.ts

@@ -1,14 +1,15 @@
 /**
  * Board layout constants
+ * Rithmomachia uses a 16x8 board (16 columns, 8 rows)
  */
 
 export const BOARD_ROWS = 8
-export const BOARD_COLUMNS = 8
+export const BOARD_COLUMNS = 16
 
 /**
- * Column labels (A-H)
+ * Column labels (A-P for 16 columns)
  */
-export const COLUMN_LABELS = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H'] as const
+export const COLUMN_LABELS = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P'] as const
 
 /**
  * Row labels (1-8)

apps/web/src/arcade-games/rithmomachia/hooks/useBoardLayout.ts

@@ -20,8 +20,8 @@ export function useBoardLayout(): BoardLayout {
   return useMemo(
     () => ({
       cellSize: 100, // SVG units per cell
-      gap: 5, // Gap between cells
-      padding: 20, // Padding around board
+      gap: 2, // Gap between cells
+      padding: 10, // Padding around board
       rows: BOARD_ROWS,
       columns: BOARD_COLUMNS,
     }),