feat(channel): KOOK 渠道适配器 + 框架兼容增强(wsutil/httpclient)

- plugins/channels/kook: config/adapter/gateway/websocket/send/message/errors — 实现 PlatformAdapter 13方法
  - WS 有状态网关: 取gateway地址→连WS→信令0/1/2/3/4/6 + 30s心跳/6s超时 + resume(拼接sn/session_id) + 指数退避重连
  - 收事件: 信令0 → UnifiedMessage(word注 channel_type/type/target_id/extra.author→字段)
  - 发消息: /message/create(频道) + /direct-message/create(私聊,修正正确端点,非user-chat) + Bearer鉴权
  - 注册 channels.go + CHANNELS_JSON 多账号 + channelbridge.configured 加 kook(bot_token非空才连)
- 框架增强: internal/channel/adapter/wsutil(连接管理/心跳/重连/resume骨架,复用gorilla,KOOK用上) + httpclient(Bearer+envelope归一,KOOK用)
- 全仓 go build/vet/test 绿, 零新依赖(复用餐gorilla), 未动telegram/qq/weixin/webhook契约
- §4.6 隔离/黑白名单/第三方边界未破坏

注: KOOK WS/WH 双模式待补(ReceiveMode), 实测需主人提供 CHANNEL_KOOK_TOKEN

plugins/channels/kook/send.go

@@ -0,0 +1,119 @@
+package kook
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/adapter"
+)
+
+// REST endpoints for sending KOOK messages.
+const (
+	channelMessagePath = "/message/create"     // channels (GROUP/BROADCAST)
+	privateMessagePath = "/direct-message/create" // private chat
+)
+
+// kookPostRequest is the shared body of the two KOOK send endpoints.
+type kookPostRequest struct {
+	Type     int    `json:"type"`
+	TargetID string `json:"target_id"`
+	Content  string `json:"content"`
+	Quote    string `json:"quote,omitempty"`
+}
+
+// SendMessage delivers the reply messages in resp. Each message goes to its own
+// channel (GROUP) or private conversation (PERSON/BROADCAST).
+func (a *Adapter) SendMessage(ctx context.Context, resp adapter.UnifiedResponse) error {
+	if err := a.requireConnected(); err != nil {
+		return err
+	}
+	for i, m := range resp.Messages {
+		if err := a.sendOne(ctx, m, resp.ReplyTo); err != nil {
+			return fmt.Errorf("kook: send message #%d: %w", i, err)
+		}
+	}
+	return nil
+}
+
+// SendProactive pushes a message not triggered by a recent inbound. KOOK allows
+// arbitrary proactive push, so this is only gated by the connection state.
+func (a *Adapter) SendProactive(ctx context.Context, msg adapter.UnifiedMessage) error {
+	if err := a.requireConnected(); err != nil {
+		return err
+	}
+	return a.sendOne(ctx, msg, "")
+}
+
+// sendOne delivers a single outbound message to its conversation, choosing the
+// send endpoint that matches the channel kind and the message type that matches
+// the content kind.
+func (a *Adapter) sendOne(ctx context.Context, m adapter.UnifiedMessage, replyTo string) error {
+	group := m.ChannelType == adapter.ChannelGroup
+	target := m.ChannelID
+	if group {
+		if target == "" {
+			target = m.GroupID
+		}
+	} else {
+		if target == "" {
+			target = m.SenderID
+		}
+	}
+	if target == "" {
+		return fmt.Errorf("kook: %w", ErrNoChatTarget)
+	}
+
+	msgType, content := outboundType(m)
+	req := kookPostRequest{Type: msgType, TargetID: target, Content: content}
+	if replyTo != "" {
+		req.Quote = replyTo
+	}
+
+	path := channelMessagePath
+	if !group {
+		path = privateMessagePath
+	}
+	if _, err := a.http.DoJSON(ctx, http.MethodPost, path, req); err != nil {
+		return err
+	}
+	a.log.Debug("sent", "type", msgType, "target", target, "group", group)
+	return nil
+}
+
+// outboundType maps a unified message to a KOOK message type and content. Text
+// falls back to kmarkdown (type 9) because the adapter declares the Markdown
+// capability; media carries the first media URL in the content field.
+func outboundType(m adapter.UnifiedMessage) (int, string) {
+	switch m.ContentType {
+	case adapter.ContentImage:
+		return kindImage, mediaURL(m.Media)
+	case adapter.ContentVoice:
+		return kindAudio, mediaURL(m.Media)
+	case adapter.ContentFile:
+		if mediaKind(m.Media) == adapter.MediaVideo {
+			return kindVideo, mediaURL(m.Media)
+		}
+		return kindFile, mediaURL(m.Media)
+	default:
+		return kindKMarkdown, m.Content
+	}
+}
+
+// mediaURL returns the first non-empty media URL.
+func mediaURL(media []adapter.Media) string {
+	for _, m := range media {
+		if m.URL != "" {
+			return m.URL
+		}
+	}
+	return ""
+}
+
+// mediaKind returns the kind of the first media entry.
+func mediaKind(media []adapter.Media) adapter.MediaKind {
+	for _, m := range media {
+		return m.Kind
+	}
+	return ""
+}