docs: status report - corrected: 5-min markets are not new, slug pattern consistent pre-v2; 3 data sources verified (subgraph + v2 chain + S3 snapshot)

docs: poly_data analysis - adopt keyset API + direct Polygon RPC for chain events (v2 contract 0xE111...996B)

docs: research report on Polymarket BTC 5-min data sources (Goldsky dead, Data API live, market just launched)

initial commit