Private atomic-swap price discovery, draft 1

Spent yesterday writing the price-discovery design for vanta-swap . The interesting part isn't the HTLC primitive — that's been solved since BIP-199 — it's the price oracle problem when both legs are private. If neither side reveals the amount, who arbitrates the rate? Three options: pre-committed price ranges (boring), threshold-decrypter set (works but adds trust), or a verifiable shuffle over a…