[SIP2.6] Onboard Maple Syrup USDC to the USDC Mainnet - Lower Risk Vault

Echoing the USDT vault comment here — this is a solid, well-scoped addition.

Having both Syrup USDC and USDT onboarded gives us a more complete RWA strategy footprint. Would also recommend that any update to $SUMR rewards consider alignment with [RFC] Extend and Adjust Vault Rewards Emissions - #2 by chrisb, to avoid incentive imbalance.

Great to see continued traction with Maple. :herb:

—jensei