fix(realtime): evict fanout 增加时效校验，防止延迟重放误踢新登录

deliverRealtimeSessionControl 分发前校验 Ctrl.Timestamp，超过 10s 的 session-control（evict）消息直接丢弃并记 skip_stale 指标，避免 consumer 重启重放 PEL / stream 积压时旧消息的 skipSid 与新会话不符导致新登录被误踢。无时间戳消息放行以兼容旧发布方。

验证：TestRealtime 3/3、regression_kick_notification 14/14、regression_mobile_kick 21/21。

server/realtime_dispatcher.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/tinode/chat/server/logs"
 	immetrics "github.com/tinode/chat/server/metrics"
@@ -223,11 +224,33 @@ func deliverRealtimeTopicMessage(envelope *store.RealtimeFanoutEnvelope, msg *Se
 	recordRealtimeFanoutDeliverResult(envelope.Kind, realtimeTargetTopic, delivered)
 }
 
+// fanoutSessionControlStaleLimit caps how long after publication a
+// session-control (evict) fanout message remains actionable. Delayed replays
+// (consumer backlog, pending-entry redelivery after restart) carry the original
+// skipSid, so a replayed evict would otherwise terminate freshly established
+// sessions whose sid differs from the stale skipSid (新登录被旧消息误踢).
+const fanoutSessionControlStaleLimit = 10 * time.Second
+
+// fanoutSessionControlStale reports whether the session-control fanout message
+// is too old to act on. Messages without a timestamp (unknown origin) are
+// delivered to stay compatible with legacy publishers.
+func fanoutSessionControlStale(msg *ServerComMessage) bool {
+	if msg == nil || msg.Ctrl == nil || msg.Ctrl.Timestamp.IsZero() {
+		return false
+	}
+	return time.Since(msg.Ctrl.Timestamp) > fanoutSessionControlStaleLimit
+}
+
 func deliverRealtimeSessionControl(envelope *store.RealtimeFanoutEnvelope, msg *ServerComMessage) {
 	if globals.sessionStore == nil {
 		immetrics.IncRealtimeFanout("deliver", envelope.Kind, envelope.TargetType, "skip_no_session_store")
 		return
 	}
+	if fanoutSessionControlStale(msg) {
+		immetrics.IncRealtimeFanout("deliver", envelope.Kind, envelope.TargetType, "skip_stale")
+		logs.Warn.Printf("redis realtime fanout: dropped stale session-control message target=%s older=%s", envelope.Target, fanoutSessionControlStaleLimit)
+		return
+	}
 	switch envelope.TargetType {
 	case realtimeTargetDevice:
 		uidText, deviceID, ok := strings.Cut(envelope.Target, ":")