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

feat(spark): add landing page queries for preview, leaderboard, recent debates

feat(spark): complete debate arena rework to conversational flow

fix(spark): update downstream components for new RoundData field names

feat(spark): add challenge persistence and update round schema

feat(spark): rewrite state machine for conversational flow

feat(spark): update types for conversational debate flow

feat: allow users to suggest custom debate topics

fix: resolve all type errors from spectrum redesign

feat(spark): DB queries, API routes, and UI components for spectrum redesign

feat(spark): spectrum data model and core types overhaul - remove lefty/righty

fix: persist ELO ratings and games_played to database

feat: redesign judge to be qualitative instead of numeric categories

feat: add Spark Micro-Debate Arena