feat: ExecutorTransferMethods helper contract

- Also sketch its use in USV2 (missing proper decoding)

foundry/src/executors/ExecutorTransferMethods.sol

@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: BUSL-1.1
+pragma solidity ^0.8.26;
+
+import "@interfaces/IExecutor.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import "@permit2/src/interfaces/IAllowanceTransfer.sol";
+import "@permit2/src/interfaces/IAllowanceTransfer.sol";
+
+error ExecutorTransferMethods__InvalidPermit2();
+
+contract ExecutorTransferMethods {
+    using SafeERC20 for IERC20;
+
+    IAllowanceTransfer public immutable permit2;
+
+    enum TransferMethod {
+        TRANSFER,
+        TRANSFERFROM,
+        TRANSFERPERMIT2,
+        NONE
+    }
+
+    constructor(address _permit2) {
+        if (_permit2 == address(0)) {
+            revert ExecutorTransferMethods__InvalidPermit2();
+        }
+        permit2 = IAllowanceTransfer(_permit2);
+    }
+
+    function _transfer(
+        IERC20 tokenIn,
+        address receiver,
+        uint256 amount,
+        TransferMethod method
+    ) internal {
+        if (method == TransferMethod.TRANSFER) {
+            tokenIn.safeTransfer(receiver, amount);
+        } else if (method == TransferMethod.TRANSFERFROM) {
+            tokenIn.safeTransferFrom(msg.sender, receiver, amount);
+        } else if (method == TransferMethod.TRANSFERPERMIT2) {
+            // Permit2.permit is called from the TychoRouter
+            permit2.transferFrom(
+                msg.sender,
+                receiver, // Does this work if receiver is not address(this)?
+                uint160(amount),
+                address(tokenIn)
+            );
+        } else {
+            // Funds are likely already in pool. Do nothing.
+        }
+    }
+}

foundry/src/executors/UniswapV2Executor.sol

@@ -4,20 +4,23 @@ pragma solidity ^0.8.26;
 import "@interfaces/IExecutor.sol";
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 import "@uniswap-v2/contracts/interfaces/IUniswapV2Pair.sol";
+import "./ExecutorTransferMethods.sol";
 
 error UniswapV2Executor__InvalidDataLength();
 error UniswapV2Executor__InvalidTarget();
 error UniswapV2Executor__InvalidFactory();
 error UniswapV2Executor__InvalidInitCode();
 
-contract UniswapV2Executor is IExecutor {
+contract UniswapV2Executor is IExecutor, ExecutorTransferMethods {
     using SafeERC20 for IERC20;
 
     address public immutable factory;
     bytes32 public immutable initCode;
     address private immutable self;
 
-    constructor(address _factory, bytes32 _initCode) {
+    constructor(address _factory, bytes32 _initCode, address _permit2)
+        ExecutorTransferMethods(_permit2)
+    {
         if (_factory == address(0)) {
             revert UniswapV2Executor__InvalidFactory();
         }
@@ -35,17 +38,18 @@ contract UniswapV2Executor is IExecutor {
         payable
         returns (uint256 calculatedAmount)
     {
+        IERC20 tokenIn;
         address target;
         address receiver;
         bool zeroForOne;
-        IERC20 tokenIn;
+        TransferMethod method;
 
-        (tokenIn, target, receiver, zeroForOne) = _decodeData(data);
+        (tokenIn, target, receiver, zeroForOne, method) = _decodeData(data);
 
         _verifyPairAddress(target);
 
         calculatedAmount = _getAmountOut(target, givenAmount, zeroForOne);
-        tokenIn.safeTransfer(target, givenAmount);
+        _transfer(tokenIn, target, givenAmount, method);
 
         IUniswapV2Pair pool = IUniswapV2Pair(target);
         if (zeroForOne) {
@@ -62,7 +66,8 @@ contract UniswapV2Executor is IExecutor {
             IERC20 inToken,
             address target,
             address receiver,
-            bool zeroForOne
+            bool zeroForOne,
+            TransferMethod method
         )
     {
         if (data.length != 61) {
@@ -72,6 +77,8 @@ contract UniswapV2Executor is IExecutor {
         target = address(bytes20(data[20:40]));
         receiver = address(bytes20(data[40:60]));
         zeroForOne = uint8(data[60]) > 0;
+        // TODO properly decode, assume encoded using just 1 byte.
+        method = TransferMethod.TRANSFER;
     }
 
     function _getAmountOut(address target, uint256 amountIn, bool zeroForOne)