[FIP - 439] sfrxUSD new strategies

## Authors Frax Core Team # Summary This proposal amends[ FIP-434](https://gov.frax.finance/t/fip-434-sfrxusd-amo-deployments-future-strategies/3786) 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...