Stabilize visitor panel ordering

server.js

@@ -1825,8 +1825,8 @@ function currentVisitors() {
     FROM visitor_sessions vs
     JOIN sites s ON s.id = vs.site_id
     LEFT JOIN visitor_profiles vp ON vp.site_id = vs.site_id AND vp.visitor_token = vs.visitor_token
-    WHERE datetime(vs.last_seen_at) >= datetime('now', '-${presence.offlineSeconds} seconds')
-    ORDER BY datetime(vs.last_seen_at) DESC
+    WHERE datetime(COALESCE(vs.last_activity_at, vs.last_seen_at)) >= datetime('now', '-${presence.offlineSeconds} seconds')
+    ORDER BY datetime(vs.first_seen_at) ASC, vs.id ASC
     LIMIT 100
   `).all();
   return rows.map((row) => formatVisitorSession(row, presence));
@@ -1861,6 +1861,7 @@ function formatVisitorSession(row, thresholds = adminPresenceSettings()) {
     countryCode,
     countryFlag: countryCode ? flagEmoji(countryCode) : "",
     sessionSeconds: sessionSeconds(row.browsing_history_json, row.first_seen_at),
+    firstSeenAt: row.first_seen_at,
     lastActivityAt: row.last_activity_at,
     lastSeenAt: row.last_seen_at
   };