feat: Add integration tests for balancer v3

Refactor BalancerV3Executor to have an inner _swapCallback method with the real swapping logic. Then we have two external methods:
- handleCallback: called by the router. Here we need to remove the first 68 bytes (4 selector + 32 dataOffset + 32 dataLength)
- swapCallback: called by the Vault directly if we are swapping against the executor directly (no router involved)

Took 1 minute

foundry/test/TychoRouterProtocolIntegration.t.sol

@@ -198,8 +198,6 @@ contract TychoRouterTestProtocolIntegration is TychoRouterTestSetup {
     }
 
     function testSingleMaverickIntegration() public {
-        vm.stopPrank();
-
         deal(GHO_ADDR, ALICE, 1 ether);
         uint256 balanceBefore = IERC20(USDC_ADDR).balanceOf(ALICE);
 
@@ -295,4 +293,25 @@ contract TychoRouterTestProtocolIntegration is TychoRouterTestSetup {
 
         vm.stopPrank();
     }
+
+    function testSingleBalancerV3Integration() public {
+        address steakUSDTlite =
+            address(0x097FFEDb80d4b2Ca6105a07a4D90eB739C45A666);
+        address steakUSDR = address(0x30881Baa943777f92DC934d53D3bFdF33382cab3);
+        deal(steakUSDTlite, ALICE, 1 ether);
+        uint256 balanceBefore = IERC20(steakUSDTlite).balanceOf(ALICE);
+
+        vm.startPrank(ALICE);
+        IERC20(steakUSDTlite).approve(tychoRouterAddr, type(uint256).max);
+
+        bytes memory callData =
+            loadCallDataFromFile("test_single_encoding_strategy_balancer_v3");
+        (bool success,) = tychoRouterAddr.call(callData);
+
+        uint256 balanceAfter = IERC20(steakUSDR).balanceOf(ALICE);
+
+        assertTrue(success, "Call Failed");
+        assertGe(balanceAfter - balanceBefore, 999725);
+        assertEq(IERC20(steakUSDR).balanceOf(tychoRouterAddr), 0);
+    }
 }