fix(kook): 私聊(临时会话)以对端用户为回复目标——修'不能是自己'40000

KOOK 临时私聊里用户→bot 事件的 target_id=bot 自己、author_id=对端用户；原 ChannelID=
target_id(bot id)，导致回复发给自己→KOOK 40000 不能是自己。修：非群聊时 ChannelID=发送者
(对端)id，回复即发给对端、每 DM 独立会话。加 TestToUnified_PrivateDmUsesPeerAsChannelID。
build/vet/test 全绿, 已重建部署.

plugins/channels/kook/message.go

@@ -91,10 +91,20 @@ func (a *Adapter) toUnifiedMessage(data json.RawMessage, frame []byte) (adapter.
 	ct, media := messageKind(ev.Type, content)
 	group := channelIsGroup(ev.ChannelType)
 
+	// KOOK temp/临时私聊: for a user→bot DM the event's target_id is the BOT's own id
+	// (the recipient), while author_id is the peer user. Using target_id as the reply
+	// target would make the bot reply to itself ("不能是自己", KOOK 40000). So for a
+	// private (non-group) message we key the conversation by the peer sender, which is
+	// also the correct reply target and keeps each DM a distinct session.
+	channelID := ev.TargetID
+	if group != adapter.ChannelGroup {
+		channelID = senderID
+	}
+
 	msg := adapter.UnifiedMessage{
 		Platform:    platformName,
 		ChannelType: group,
-		ChannelID:   ev.TargetID,
+		ChannelID:   channelID,
 		SenderID:    senderID,
 		SenderName:  senderName,
 		Content:     content,