V4 fee adapter

[ccashwell]

This PR introduces tiered protocol fee support for Uniswap V4, enabling governance to collect protocol fees from V4 pools with a waterfall resolution pattern matching the V3 fee structure established in the UNIfication proposal.

Summary

• V4FeeAdapter contract implementing tiered protocol fees with waterfall resolution: pool override → fee tier → default
• Governance proposal script to activate V4 fees and set the adapter as protocol fee controller
• Deployer contracts for Mainnet and Unichain
• Comprehensive unit and fork tests with exact fee validation

Changes

New Contracts

• src/feeAdapters/V4FeeAdapter.sol - Tiered fee controller with waterfall resolution
• src/interfaces/IV4FeeAdapter.sol - Interface with comprehensive NatSpec

Scripts

• script/05_V4FeeSwitchProposal.s.sol - Governance proposal to activate fees
• script/06_DeployV4Mainnet.s.sol - Mainnet deployment script
• script/07_DeployV4Unichain.s.sol - Unichain deployment script
• script/deployers/V4MainnetDeployer.sol - Mainnet deployer contract
• script/deployers/V4UnichainDeployer.sol - Unichain deployer contract

Tests

• test/V4FeeAdapter.t.sol - unit tests covering all V4 fee adapter functionality
• test/V4ProtocolFees.fork.t.sol - fork tests validating against real V4 pool interactions

Technical Notes

• protocol fee values are packed (lower 12 bits for zeroForOne, upper 12 bits for oneForZero swaps)
• The adapter stores single-direction fees and packs them symmetrically when queried
• Uses uint24.max as sentinel for "explicitly zero fee" (distinct from "not set")
• Fork tests validate exact fee collection with 1 wei tolerance for V4's internal rounding