feat(web/trades): force-dynamic + auto-refresh every 30s

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/components/TradesRefresher.tsx

@@ -0,0 +1,22 @@
+"use client";
+import { useEffect, useState } from "react";
+import { useRouter } from "next/navigation";
+
+export default function TradesRefresher() {
+  const router = useRouter();
+  const [lastUpdated, setLastUpdated] = useState<Date>(new Date());
+
+  useEffect(() => {
+    const id = setInterval(() => {
+      router.refresh();
+      setLastUpdated(new Date());
+    }, 30_000);
+    return () => clearInterval(id);
+  }, [router]);
+
+  return (
+    <span className="text-xs text-ink-ter font-mono">
+      Updated {lastUpdated.toLocaleTimeString()}
+    </span>
+  );
+}