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

fix: leaderboard tracking, score bugs, mobile admin, OG image

feat: make multiplayer matchmaking snappy and engaging

fix: persist ELO ratings and games_played to database

fix(cosmetics): wire all four cosmetic categories to their visible elements

fix(multiplayer): submit leaderboard entry on match completion

UX: decrease question transition delays across all modes for faster, snappier gameplay

Fix Quick Match multiplayer sync and solo scoring feedback

feat: add room-based multiplayer, Game Night, and 124 new questions

feat: upgrade all pages with Lucide icons, glow effects, and confetti

feat: multiplayer — matchmaking, 1v1 match with bot demo, match results with ELO