Single-metric z-score threshold trigger — pass any metric_id, operator (gt/lt/gte/lte/abs_gt), and threshold. Returns the same institutional envelope as the presets: 5-year backtest, Sortino, MDD, profit factor, walk-forward, regime context. Applies to any of 440+ metrics across 8 factor classes. Backtests run over the CRYPTYX 200+ tracked digital assets — BTC, ETH, SOL, top-cap + long-tail coverage.