Market indicators grouped by asset class

Market indicators: indexes, commodities, rates, crypto, options sentiment.

Route-level 12s timeout (2026-04-26 P0): a HAR trace from prod showed two consecutive /api/indicators requests timing out at the frontend's 20s ceiling with net::ERR_ABORTED, leaving the "Loading market data..." text stuck on the macro view. Root cause: when FMP is over quota the underlying fetch_market_indicators blocks waiting on the FMP HTTP timeout (which exceeds 20s). Now we cap the route at 12s and return an empty payload on timeout — frontend renders an empty grid honestly rather than a perpetual loader.