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

fix: batch of 5 stability fixes

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

fix: prevent challenge-me mode from hanging on infinite spinner at end of game

Fix Quick Match multiplayer sync and solo scoring feedback

Fix Challenge Me 3-round system + improve Nebula Arcade drawer

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

feat: add mini-game shared infrastructure (types, registry, high-scores)

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

feat: question system with categories, shuffle, progressive difficulty, and seeder

feat: game engine state machine with reducer pattern

feat: core types, scoring logic, and ELO rating system with tests