Retrieve session details
ses_xxx) is unguessable and acts as the access token for checkout pages (same pattern as Stripe).
Three access tiers:
sy_pub_*: Restricted checkout-safe fields only (amount, status, fees, destination chain/token, checkoutUrl, expiresAt). No metadata, wallet addresses, or accountId.sy_auth_*: Full details on own sessions only.sy_secret_*: Full details on all sessions under the partner.sy_pub_* | sy_secret_* | sy_auth_*
ses_abc123)