Blend positions carry USD, and Soroswap positions are served

Blend positions on mainnet come back priced, and Soroswap joins Blend and Aquarius in the Positions API.

• A Blend position returns per pool: supply, collateral and borrowings leg by leg, each with its USD value and yield, plus a net value and a health factor for the pool.
• Soroswap positions are served per pair: LP shares and the wallet’s share of the pool, with closed positions excluded. Where no price is available for one leg of a pair, the USD value is null with the reason attached rather than a fabricated zero.
• Blend activity records carry the asset and the amount for every event.