fix(ui): remove Duration label from correlation row, keep value only

ui/src/pages/Exchanges/ExchangeHeader.tsx

@@ -126,7 +126,7 @@ export function ExchangeHeader({ detail, onCorrelatedSelect }: ExchangeHeaderPro
           const starts = chain.map((ce: any) => new Date(ce.startTime).getTime()).filter((t: number) => !isNaN(t));
           const ends = chain.map((ce: any) => new Date(ce.endTime ?? ce.startTime).getTime() + (ce.durationMs ?? 0)).filter((t: number) => !isNaN(t));
           const totalMs = starts.length > 0 && ends.length > 0 ? Math.max(...ends) - Math.min(...starts) : 0;
-          return totalMs > 0 ? <span className={styles.chainTotal}>Duration: {formatDuration(totalMs)}</span> : null;
+          return totalMs > 0 ? <span className={styles.chainTotal}>{formatDuration(totalMs)}</span> : null;
         })()}
       </div>
     </div>