fix: decode Uniswap V2 exact-out swaps, input amount shown as a maximum (closes #283)

decode() had no arm for Universal Router command 0x09, so the approval
screen named the step and showed no token or amount. It now takes the
path's first token with amountInMax as the input side and the last token
with amountOut as the output side, through setInputOnce() and setOutput()
like 0x08. amountInMax is the most the swap may spend, so the Amount line
reads "Up to <amount>", including the value the wait and error screens
show. The eslint-disable comment on decodeV2SwapExactOut() is gone.

Model: opus-5-5

tests/uniswap.test.js

@@ -75,6 +75,14 @@ function encodeV2SwapExactIn(recipient, amountIn, amountOutMin, pathAddrs) {
     );
 }
 
+// Helper: encode a V2_SWAP_EXACT_OUT input (command 0x09)
+function encodeV2SwapExactOut(recipient, amountOut, amountInMax, pathAddrs) {
+    return coder.encode(
+        ["address", "uint256", "uint256", "address[]", "bool"],
+        [recipient, amountOut, amountInMax, pathAddrs, true],
+    );
+}
+
 // Helper: encode a V3_SWAP_EXACT_IN input (command 0x00)
 function encodeV3SwapExactIn(recipient, amountIn, amountOutMin, pathTokens) {
     // V3 path: token(20) + fee(3) + token(20) ...
@@ -223,6 +231,36 @@ describe("uniswap decoder", () => {
         expect(minOut.value).toContain("WETH");
     });
 
+    // Buy exactly 0.5 WETH for at most 1,500 USDC, paid by the user, sent to
+    // the caller (the router's MSG_SENDER recipient, address(1)).
+    test("decodes V2_SWAP_EXACT_OUT, stating the input amount as a maximum", () => {
+        const data = buildExecute(
+            "0x09", // V2_SWAP_EXACT_OUT
+            [
+                encodeV2SwapExactOut(
+                    "0x0000000000000000000000000000000000000001",
+                    500000000000000000n, // amountOut: 0.5 WETH
+                    1500000000n, // amountInMax: 1,500 USDC (6 decimals)
+                    [USDC_ADDR, WETH_ADDR],
+                ),
+            ],
+            1767225600n,
+        );
+
+        const result = uniswap.decode(data, ROUTER_ADDR);
+        expect(result.name).toBe("Swap USDC → WETH");
+        expect(detail(result, "Token In").address).toBe(USDC_ADDR);
+        expect(detail(result, "Token Out").address).toBe(WETH_ADDR);
+
+        // The wait and error screens show rawValue as the amount, so it says
+        // "Up to" as well.
+        const amount = detail(result, "Amount");
+        expect(amount.value).toBe("Up to 1500.0000 USDC");
+        expect(amount.rawValue).toBe("Up to 1500.0000");
+
+        expect(detail(result, "Min. received").value).toBe("0.5000 WETH");
+    });
+
     test("decodes V3_SWAP_EXACT_IN with known tokens", () => {
         const data = buildExecute(
             "0x00", // V3_SWAP_EXACT_IN