Add datetime for chat

frontend/src/UserMessage.jsx

@@ -1,10 +1,9 @@
-// UserMessage.jsx
+// src/UserMessage.jsx
 import React from "react";
 
-export default function UserMessage({ content, theme }) {
+export default function UserMessage({ content, theme, timestamp }) {
   return (
-    // This outer div aligns the *bubble* to the right
-    <div className="mb-2 d-flex justify-content-end">
+    <div className="mb-2 d-flex flex-column align-items-end">
       <div
         className={`p-2 rounded ${theme.userBg}`}
         style={{
@@ -24,8 +23,37 @@ export default function UserMessage({ content, theme }) {
           {content}
         </pre>
       </div>
+      {timestamp && (
+        <div
+          style={{
+            fontSize: "0.75rem",
+            color: "#666",
+            marginTop: "0.2rem",
+            marginRight: "0.25rem"
+          }}
+        >
+          {formatDateTime(timestamp)}
+        </div>
+      )}
     </div>
   );
 }
 
+// Same helper used in AssistantMessage
+function formatDateTime(dateTime) {
+  try {
+    const date = new Date(dateTime);
+    return date.toLocaleString(undefined, {
+      year: "numeric",
+      month: "short",
+      day: "numeric",
+      hour: "2-digit",
+      minute: "2-digit",
+      second: "2-digit"
+    });
+  } catch {
+    return dateTime;
+  }
+}
+