feat: remove Supabase, bundle questions locally, use JSON DB + API

feat: easter eggs — triple-click admin access + TRIVIAMASTER name unlock

Fix stale player ID causing leaderboard/coins/achievements to fail

feat: add achievement toast notifications, trophy room page, and header nav updates

feat: replace emoji icons with Lucide icons in Header, add glow border

feat: polish — page transitions, sound integration, screen shake, remaining files