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

fix(spark): Batches 2 + 3 — atomic ELO, real DB IDs, polish

fix(spark): Batch 1 — practice ELO leak, schema alignment, RLS tightening

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

feat: improve UX and player tracking

feat: add Spark Micro-Debate Arena

feat: cross-device account linking via 6-char sync code

feat: per-session location tracking + admin player intelligence

feat: player signup metadata tracking + shop purchase visual feedback

fix: implement player name change DB sync and policies

feat: implement cosmic shop logic, db functions, and policies for purchasing and equipping cosmetics

fix: resolve foreign key uuid issues preventing leaderboard submission & guarantee true randomness when fetching question batches

fix: apply v2 migrations to db and update leaderboard UI/queries to match new schema

feat: fix question system + add HF Spaces deployment

fix: address code review findings (RLS delete policy, Starfield context, achievement toasts)

feat: add platform features schema migration (achievements, cosmetics, star coins)

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