Get typed live price observations as JSON-LD

Public, read-only endpoint; no API key or authentication is required. Returns the same complete nine-market Binance Spot snapshot as an explicit Schema.org DataFeed. Each DataFeedItem contains an Observation whose observationAbout is an ExchangeRateSpecification with a UnitPriceSpecification. Decimal prices are strings that preserve Binance source precision; currency is the base asset and priceCurrency is USDT. dateModified is BTC War generation time; observationDate is Binance closeTime. The response fails closed if any required market is missing, invalid or stale.