fix: a swap deadline later than a date can hold is stated in words (closes #437)

decode() rendered the Deadline line with toISOString(), which throws on a
date past 275760-09-13, the last a JavaScript date can hold. A later
deadline, such as the uint256 maximum, therefore left the whole swap
undecoded, with nothing saying why. That line now reads
"After 275760-09-13 00:00:00 (no deadline in practice)".

Model: opus-5-5

src/shared/uniswap.js

@@ -724,10 +724,15 @@ function decode(data, toAddress, sources) {
 
         details.push({ label: "Steps", value: commandNames.join(" \u2192 ") });
 
+        // A JavaScript date reaches only to 275760-09-13 00:00:00 UTC. A
+        // later deadline, such as the uint256 maximum, makes an invalid date,
+        // and toISOString() throws on one, so that deadline is said in words.
         const deadlineDate = new Date(Number(deadline) * 1000);
         details.push({
             label: "Deadline",
-            value: deadlineDate.toISOString().replace("T", " ").slice(0, 19),
+            value: isNaN(deadlineDate.getTime())
+                ? "After 275760-09-13 00:00:00 (no deadline in practice)"
+                : deadlineDate.toISOString().replace("T", " ").slice(0, 19),
         });
 
         return {