feat: implement digit entry in edit mode (Phase 40.3.3)

- Add setCell method to useBoard to update board state
- Handle digit keys 1-9 in edit mode in useCursor
- Move boardRendered counter to useBoard for proper cursor re-rendering
- Fix golden glow disappearing after digit entry
- Digits display with .user-entered class via renderer

src/useGame.ts

@@ -8,15 +8,14 @@ import { useCursorRender } from './useCursor/useCursorRender';
 export function useGame(options: GameOptions = {}, platformHook?: unknown): GameManager {
   const { difficulty = 'easy' } = options;
   const board = useBoard();
-  const { containerRef, renderBoard, generateBoard } = board;
+  const { containerRef, renderBoard, generateBoard, boardRendered } = board;
   
   const gameStatusManager = useGameStatus();
   const { gameStatus } = gameStatusManager;
   
   const [keyLog, setKeyLog] = useState<{ key: string; timestamp: number }[]>([]);
-  const [boardRendered, setBoardRendered] = useState(0);
   
-  const cursor = useCursor(gameStatusManager, containerRef);
+  const cursor = useCursor(gameStatusManager, containerRef, board);
   const cursorPosition = cursor.position();
   const cursorMode = cursor.mode();
   
@@ -24,17 +23,14 @@ export function useGame(options: GameOptions = {}, platformHook?: unknown): Game
 
   useEffect(() => {
     renderBoard();
-    setBoardRendered(prev => prev + 1);
   }, []);
 
   useEffect(() => {
     if (gameStatus === 'started') {
       generateBoard(difficulty);
       renderBoard();
-      setBoardRendered(prev => prev + 1);
     } else if (gameStatus === 'waiting') {
       renderBoard();
-      setBoardRendered(prev => prev + 1);
     }
   }, [gameStatus, difficulty]);