- Added lib/dateUtils.ts for consistent timezone handling
- Updated app/page.tsx and app/api/daily/route.ts to use Europe/Berlin timezone
- Updated lib/gameState.ts to sync client-side daily check with server time
- Exposed TZ env var to client in next.config.ts
- Add personal statistics with badges for each attempt count
- Track solved puzzles per attempt (1-6) and failed attempts
- Display statistics after game completion
- Fix clipboard API issue with fallback method
- Add footer with attribution
