Agent skills for Alpaca's Trading API and Broker API: drop-in SKILL.md files for AI coding assistants

US stock market data for AI coding assistants — zero-auth, official sources. CBOE options with full Greeks + 0DTE flow, FINRA market-wide short volume, SEC EDGAR filing stream, and a free market-wide screener. 13 layers, 30+ endpoints, 11 sources. Every source labeled with its compliance tier.