Reposition README: lead with cross-platform, soften claims, add Myriad + research links

Add sample_markets_lookup.parquet — makes candle market_id joinable to titles/outcomes

Fix README: accurate row counts/date ranges, add lookup join table docs

Update README.md

Add Manifold 1h OHLCV sample (top 60 markets, last 6 months)

Add Polymarket 1h OHLCV sample (top 70 markets, last 6 months)

Filter out Kalshi markets from metadata — only Polymarket and Manifold

Remove Kalshi, fix license to other, update citation year to 2026, add metadata note

Add full markets metadata (8.18M markets)

Rewrite dataset card - factual, no sales copy

Add dataset card

initial commit