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_test.go

@@ -7,6 +7,30 @@ import (
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/adapter"
 )
 
+func TestToUnified_PrivateDmUsesPeerAsChannelID(t *testing.T) {
+	t.Parallel()
+	a := New(Config{BotToken: "x"})
+	a.setBotIdentity(botIdentity{ID: "bot-1", Username: "Cyrene", Nickname: "Cyrene"})
+	// KOOK temp/临时私聊: the user→bot DM event's target_id is the BOT (bot-1),
+	// author_id is the peer user. ChannelID must be the peer so the reply targets the
+	// user, not the bot ("不能是自己" otherwise).
+	data := json.RawMessage(`{
+		"channel_type":"PERSON","type":1,"target_id":"bot-1","author_id":"u-1",
+		"content":"在吗","msg_id":"m-dm","msg_timestamp":1700000000000,"nonce":"",
+		"extra":{"type":1,"author":{"id":"u-1","username":"alice","nickname":"Alice"}}
+	}`)
+	msg, ok := a.toUnifiedMessage(data, nil)
+	if !ok {
+		t.Fatal("expected a deliverable private message")
+	}
+	if msg.ChannelID != "u-1" {
+		t.Errorf("private ChannelID = %q, want peer u-1", msg.ChannelID)
+	}
+	if msg.SenderID != "u-1" {
+		t.Errorf("SenderID = %q, want u-1", msg.SenderID)
+	}
+}
+
 func TestToUnified_DropsSelfEcho(t *testing.T) {
 	t.Parallel()
 	a := New(Config{BotToken: "x"})