fix: a V4 SETTLE of ETH paid from the router reads as moved from the sender (closes #682)

V4Router pays a SETTLE of ETH from the router's own ETH, whichever payer
it names. The router holds the transaction's value. So a SETTLE of ETH
that names the router as payer now counts as paid by the user.

When an earlier step left ETH in the router, such a SETTLE gets lines of
its own. Its line reads "Up to" and its amount, and that amount never
joins the Amount total. When the decoder does not know the SETTLE's
amount, as for CONTRACT_BALANCE, its line reads "Unknown (could not be
decoded)", also on the step that sets the input side.

One existing row in tests/uniswapRecipient.test.js now expects the ETH
lines. Its SETTLE spends all the router's ETH, the transaction's value
included.

Model: opus-5-5

tests/uniswapRecipient.test.js

@@ -1661,9 +1661,18 @@ describe("any token left in the router is not received", () => {
             ),
             min: "1990.0000 USDC",
         },
-        {
-            kind: "a swap paying WETH to the router, an UNWRAP_WETH into the router, then a V4 swap settling all the ETH from the router",
-            data: execute(
+    ])("$kind reads as a swap paid to the user", ({ data, min }) => {
+        const result = decode(data);
+        expect(labels(result)).toEqual(PAID_TO_USER);
+        expect(detail(result, "Min. received").value).toBe(min);
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/682 — the SETTLE spends all
+    // the router's ETH, the transaction's value included, so the sender pays
+    // an amount the calldata does not state.
+    test("a swap paying WETH to the router, an UNWRAP_WETH into the router, then a V4 swap settling all the ETH from the router reads as a swap paid to the user", () => {
+        const result = decode(
+            execute(
                 swapToWeth(ADDRESS_THIS),
                 unwrapWeth(ADDRESS_THIS),
                 v4Swap(
@@ -1672,12 +1681,23 @@ describe("any token left in the router is not received", () => {
                     takeAll(USDC),
                 ),
             ),
-            min: "1990.0000 USDC",
-        },
-    ])("$kind reads as a swap paid to the user", ({ data, min }) => {
-        const result = decode(data);
-        expect(labels(result)).toEqual(PAID_TO_USER);
-        expect(detail(result, "Min. received").value).toBe(min);
+        );
+        expect(labels(result)).toEqual([
+            "Protocol",
+            "Token In",
+            "Amount",
+            "Moved from the sender",
+            "Token moved",
+            "Moved to",
+            "Token Out",
+            "Min. received",
+            "Steps",
+            "Deadline",
+        ]);
+        expect(detail(result, "Moved from the sender").value).toBe(
+            "Unknown (could not be decoded)",
+        );
+        expect(detail(result, "Min. received").value).toBe("1990.0000 USDC");
     });
 });