fix: any token a swap leaves in the router keeps it from reading as received (closes #606)

The decoder checked only the swap's output for being left in the router.
It now records every token a step pays the router, the WETH of a
WRAP_ETH and the rest of a V4 SETTLE taken to the router among them, and
any token still there after the last step gets a Paid to line naming it,
so the minimum reads Min. paid out. Steps that spend all the router holds
of a token count as spending it, and so do swap steps from the router
that together spend what a WRAP_ETH stated, when the router held no WETH
before it. A SETTLE of OPEN_DELTA from the router counts only in the
plain shape of Uniswap's own routes.

Model: opus-5-5

tests/uniswap.test.js

@@ -739,7 +739,9 @@ describe("uniswap decoder", () => {
     });
 
     // Paid in ETH, with an exact-out step, the last swap step buys WETH, so
-    // UNWRAP_WETH makes the output ETH.
+    // UNWRAP_WETH makes the output ETH. That step is paid by the user, so the
+    // USDC the exact-out step bought stays in the router, and the minimum is
+    // not received (https://git.eeqj.de/sneak/AutistMask/issues/606).
     test("an ETH-paid swap whose last step buys WETH, then UNWRAP_WETH, shows ETH", () => {
         const data = buildExecute(
             solidityPacked(
@@ -767,7 +769,7 @@ describe("uniswap decoder", () => {
 
         const result = uniswap.decode(data, ROUTER_ADDR, "0x1", {}, USER_ADDR);
         expect(detail(result, "Token Out").value).toBe("ETH");
-        expect(detail(result, "Min. received").value).toBe("0.4000 ETH");
+        expect(detail(result, "Min. paid out").value).toBe("0.4000 ETH");
     });
 
     // Sepolia's WETH is a different contract; UNWRAP_WETH makes it ETH too.