Implement Paxos oracle with hardcoded 1:1 USDC↔Paxos token rate

[mpetrunic]

Summary

Implement a Paxos oracle that returns a hardcoded 1:1 rate between USDC and Paxos-issued tokens (USDG, PYUSD).

Motivation

Paxos swaps are priced at a fixed 1:1 ratio between USDC and the Paxos stablecoins. An on-chain oracle exposing this hardcoded 1:1 rate is needed for the contracts to value/settle these swaps.

Scope

• New Paxos oracle returning a fixed 1:1 rate for USDC ↔ USDG and USDC ↔ PYUSD.

Parent: sprintertech/sprinter-api#1161