- Created core/config.js with SUPABASE_URL, STOCKFISH_URL, DEFAULT_RATING
- login.js, register.js, realtime.js now import from shared config
- chess/game.js and bot-select.js use STOCKFISH_URL constant
- multiplayer.js uses DEFAULT_RATING from config
- ludo/game.js: named TURBO_SPEED constant
- table.js: removed dead `disabled = false` code path
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>