Fix: split unread marker effect to avoid clearing marker on readNewestAction

The single effect with reportLastReadTime in the dependency array caused
unreadMarkerTime to update whenever readNewestAction marked messages as
read, immediately clearing the unread indicator. Split into two effects:
one for report switches (original behavior) and one that only fires when
reportLastReadTime transitions from empty to a real value (sign-in case).

Co-authored-by: Pujan Shah <Pujan92@users.noreply.github.com>

Author: MelvinBot

src/pages/inbox/report/ReportActionsList.tsx

@@ -259,15 +259,20 @@ function ReportActionsList({
      */
     const [unreadMarkerTime, setUnreadMarkerTime] = useState(reportLastReadTime);
     useEffect(() => {
-        // When lastReadTime is empty (e.g. data hasn't loaded yet after sign-in),
-        // skip the update so we don't place the marker at the wrong position.
-        if (reportLastReadTime === '') {
-            return;
-        }
         setUnreadMarkerTime(reportLastReadTime);
 
         // eslint-disable-next-line react-hooks/exhaustive-deps
-    }, [report.reportID, reportLastReadTime]);
+    }, [report.reportID]);
+
+    // When lastReadTime transitions from empty to a real value (e.g., data hasn't
+    // loaded yet after sign-in), update the marker so it uses the fresh value
+    // instead of the empty string from initial mount.
+    useEffect(() => {
+        if (reportLastReadTime !== '' && unreadMarkerTime === '') {
+            setUnreadMarkerTime(reportLastReadTime);
+        }
+        // eslint-disable-next-line react-hooks/exhaustive-deps
+    }, [reportLastReadTime]);
 
     const prevUnreadMarkerReportActionID = useRef<string | null>(null);