Same-game parlay correlation pricer.

Body: {legs: [<leg>, ...]}. Each leg: sport_key, market, side, book (always); player + line (player props); home_team + away_team + game_date (always).

Response: per-leg marginals, independent baseline, literature- correlation-adjusted parlay implied, book payout multiplier, EV ratio. Unpriced legs land in unpriced_legs; the parlay estimate collapses to null when any leg is unpriced (we NEVER fabricate a missing marginal). Correlation audit names the literature source used per pair.

Cost: 10 base + 5 credits per leg. Min 15.

Gated by SGP_PRICER_ENABLED=1. Default OFF; returns 503 with explanatory body when disabled.