docs(samples): update PlaytimeReporter example to use WaitForSecondsRealtime

Changed the PlaytimeReporter coroutine in the Assets/Unity example to use WaitForSecondsRealtime instead of WaitForSeconds.
This ensures that playtime reporting continues even when the game is paused (Time.timeScale = 0).

Author: DevD4v3

assets/unity/PlaytimeReporter.cs

@@ -51,7 +51,7 @@ private IEnumerator ReportCoroutine()
         {
             while (true)
             {
-                yield return new WaitForSeconds(_reportIntervalSeconds);
+                yield return new WaitForSecondsRealtime(_reportIntervalSeconds);
                 double hoursPlayed = (DateTime.UtcNow - _lastReportTime).TotalHours;
                 _lastReportTime = DateTime.UtcNow;