Act as a senior blockchain developer. I want to build a crypto arbitrage web app step-by-step. First, let's plan the smart contract for Ethereum using Solidity. It must use Aave flash loans (borrowing money without collateral). The contract should look for price gaps between Uniswap and Sushiswap. All fees must be paid from the profit. If there is no profit, the trade should stop and fail. Before ...