Nexis Data Hub: full repo catalog added

The brain_repos table has been seeded with the complete Nexis data source catalog (60+ entries) covering: primary normalized connectors (OpenBB, CCXT, PMXT, QuantConnect LEAN, OpenFIGI), US equities (Alpaca, Finnhub, Alpha Vantage, yfinance, Twelve Data, Stooq), global equities (AKShare), options (ThetaData, Tradier, CBOE), crypto (CoinGecko, CoinMetrics, DefiLlama, Dune, The Graph, Deribit, Hyperliquid), prediction markets (Polymarket, Kalshi, PredictOS, PolyBench), macro/government (FRED, ALFRED, BLS, BEA, US Treasury, CFTC, World Bank, IMF, OECD), filings (SEC EDGAR, edgartools, sec-edgar-downloader, Federal Register, Congress.gov), and news/alt data (Marketaux, GDELT, Alpaca News, EIA, NOAA). The Nexis Data Hub now has two sub-tabs: Cron Adapters (existing) and Repo Catalog (new) with category + tier filters, primary connector badges, and GitHub link buttons.