fix: a swap's WETH minimum reads as ETH only when all its WETH reaches the UNWRAP_WETH (closes #642)

Between the step that set the output side and the UNWRAP_WETH, only a
step the decoder read that is a PERMIT2_PERMIT, a BALANCE_CHECK_ERC20,
or a SWEEP, TRANSFER, PAY_PORTION or PAY_PORTION_FULL_PRECISION of a
token other than WETH, and not of ETH to a WETH contract, keeps the
swap's WETH minimum as an ETH minimum; any other step leaves ETH with no
minimum. After an UNWRAP_WETH whose recipient is the router or cannot be
read, any later step but those makes the swap read WETH with no minimum.
Only a step that sets the output side again brings back ETH or a
minimum. A WETH fee paid by PAY_PORTION before the UNWRAP_WETH now shows
no minimum. README Display Consistency states the same rule.

Model: opus-5-5

tests/uniswapRecipient.test.js

@@ -1067,6 +1067,42 @@ describe("what reaches the UNWRAP_WETH of the swap's WETH", () => {
         expect(detail(result, "Token Out").value).toBe("ETH");
         expect(detail(result, "Min. received").value).toBe("1.0000 ETH");
     });
+
+    // The first swap is for at least 0.5 WETH and the second for at least
+    // 1 WETH. The second sets the output side again, so the first
+    // UNWRAP_WETH into the router no longer bears on it.
+    test.each([
+        { kind: "a V3 swap step", step: swapToWeth(ADDRESS_THIS) },
+        {
+            kind: "a V4 step that TAKEs its WETH to the router",
+            step: v4Swap(
+                SWAP_USDT_FOR_WETH,
+                SETTLE_USDT,
+                take(WETH, ADDRESS_THIS),
+            ),
+        },
+    ])(
+        "a swap paying WETH to the router, an UNWRAP_WETH into the router, a SWEEP of its ETH to the user, then $kind and an UNWRAP_WETH to the user, reads as ETH with the second swap's minimum",
+        ({ step }) => {
+            const result = decode(
+                execute(
+                    v3SwapExactIn(
+                        ADDRESS_THIS,
+                        USDT_2000,
+                        ONE_WETH / 2n,
+                        USDT,
+                        WETH,
+                    ),
+                    unwrapWeth(ADDRESS_THIS),
+                    sweep(ZERO, MSG_SENDER),
+                    step,
+                    unwrapWeth(MSG_SENDER),
+                ),
+            );
+            expect(result.name).toBe("Swap USDT → ETH");
+            expect(detail(result, "Min. received").value).toBe("1.0000 ETH");
+        },
+    );
 });
 
 // https://git.eeqj.de/sneak/AutistMask/issues/606: any token a step pays the