Integrated i18n system throughout the application with `useLanguage` hook providing translation function and language state. Added bilingual support to all user-facing strings in App.jsx (password validation, error messages, game creation, sheet sections), AdminPanel (user management, form validation, status messages), AdminSettingsModal (SMTP configuration), ChipModal, DesignModal, GamePickerCard (lobby interface,
Added read-only enforcement for finished games by checking `winner_user_id` in backend PATCH endpoint and frontend sheet interactions. Implemented GameStartCelebration component with confetti burst, animated overlay card, and pulsing rune icon. Enhanced splash screen with orbiting border animation, sparkle effects, and title rise transition. Added haptic feedback (vibration) to sheet
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