Swap tokens and read pool state on Uniswap V4 (Base, Ethereum). Use when the agent needs to: (1) swap ERC20 tokens or ETH via Uniswap V4, (2) get pool info (price, tick, liquidity, fees), (3) find the best pool for a token pair, (4) quote expected swap output via the on-chain V4Quoter, (5) set up Permit2 approvals for the Universal Router, or (6) execute exact-input swaps with proper slippage protection. Supports Base and Ethereum mainnet, plus Base Sepolia testnet. TypeScript with strict types. Write operations need a private key via env var.