- Add surrender button to game controls
- Add game-over modal with stats and rematch option
- Add surrender confirmation modal
- Add all CSS styling for new modals and buttons
- Add surrender-rematch.js with global helper functions
- Update multiplayer.js constructor to track opponent for rematch
- Added ID to turn label for easier updates
- Updated multiplayer.js to use turnLabel ID
- Reset turn label when switching modes or resetting game
- Improved UX by keeping player/turn info together
- Created storage.js wrapper with IndexedDB support
- Automatic fallback to localStorage if IndexedDB unavailable
- Updated all username storage calls to use async API
- Better performance and more storage capacity
- Improved PWA compatibility
Benefits:
- 50MB+ storage vs 5-10MB localStorage
- Async API doesn't block main thread
- Better for future features (game history, stats, etc.)
- Add polling mechanism to wait for window.game initialization
- Disable multiplayer button until game is fully initialized
- Enable button in DOMContentLoaded after game creation
- Prevents 'Game instance not found' error on production
This fixes the critical issue where clicking Multiplayer too quickly
would fail because window.game wasn't ready yet.
