SCPX-XS: Exchange Service

[7-of-9]

There should exist a native exchange-connected asset transfer service to supplement, replace and/or improve on current asset exchange functionality.

The envisaged design is that a server Scoop wallet (scpx-xs-wallet) would hold a hot float of funds of each asset type and respond to requests from a coordinating DB-backed service that uses RPC to:

• register one-time-use receive addresses in scpx-xs-wallet
• monitor for user-requested inbound flows, and
• upon confirmed receipts, execute outbound payment.

An periodic (separate) process would need to use exchange APIs to perform corresponding asset conversions to keep scpx-xs-wallet assets sufficiently balanced.

Requires #4