[FIP - 439] sfrxUSD new strategies

Summary

Authors Frax Core Team # Summary This proposal amends FIP-434 by adding several new sfrxUSD yield strategies to the approved AMO whitelist. These additions expand sfrxUSD’s on-chain yield opportunities through new holdings, Curve liquidity pools, and Pendle market integrations while maintaining the conservative risk framework and governance-guided allocation rules established under FIP-434. # Background...