feat: 品牌裁剪弹窗/Markdown 行内短代码与详情视频块等

新增：
- BrandCropModal 品牌图裁剪弹窗 + cropImage 工具
- Markdown 行内短代码（inlineShortcodes + remark 插件）
- MdDetails 折叠块、MdVideo 视频块组件
- directiveBlocks/inlineShortcodes 测试

其它：
- 聊天后端（handler/service chat）调整
- Markdown 渲染链路、编辑器、全局样式与品牌相关面板更新

backend/service/chat.go

@@ -131,7 +131,7 @@ func (s *ChatService) Membership(roomID, userID uint) (*model.ChatRoomMember, er
 	return s.membership(s.db, roomID, userID)
 }
 
-// unreadCounts 批量计算访问者在给定群集合中的未读数（消息 ID 大于已读水位、且排除本人发送）
+// unreadCounts 批量计算访问者在给定群集合中的未读数（消息 ID 大于已读水位、且排除本人发送与系统提示）
 func (s *ChatService) unreadCounts(userID uint, roomIDs []uint) map[uint]int64 {
 	out := make(map[uint]int64)
 	if userID == 0 || len(roomIDs) == 0 {
@@ -141,7 +141,7 @@ func (s *ChatService) unreadCounts(userID uint, roomIDs []uint) map[uint]int64 {
 	s.db.Table("chat_messages AS m").
 		Select("m.room_id AS room_id, count(*) AS cnt").
 		Joins("JOIN chat_room_members AS rm ON rm.room_id = m.room_id AND rm.user_id = ?", userID).
-		Where("m.room_id IN ? AND m.id > rm.last_read_message_id AND m.sender_id <> ? AND m.deleted_at IS NULL AND m.recalled_at IS NULL", roomIDs, userID).
+		Where("m.room_id IN ? AND m.id > rm.last_read_message_id AND m.sender_id <> ? AND m.deleted_at IS NULL AND m.recalled_at IS NULL AND m.is_system = ?", roomIDs, userID, false).
 		Group("m.room_id").
 		Scan(&rows)
 	for _, r := range rows {
@@ -767,8 +767,10 @@ func (s *ChatService) Kick(operatorID, roomID, targetID uint, oversee bool) erro
 	return s.removeMember(roomID, targetID)
 }
 
-// SendSystemMessage 向房间落库一条系统提示消息（sender_id=0，is_system=true），
-// 并推进房间 last_message_id 与 updated_at。失败返回 nil + error。
+// SendSystemMessage 向房间落库一条系统提示消息（sender_id=0，is_system=true）。
+// 只推进房间 updated_at，不推进 last_message_id：系统提示不作为会话预览，
+// 也不参与排序顶置，避免禁言/解禁等管理动作在会话列表伪装成「新消息」。
+// 失败返回 nil + error。
 func (s *ChatService) SendSystemMessage(roomID uint, content string) (*model.ChatMessage, error) {
 	msg := &model.ChatMessage{
 		RoomID:    roomID,
@@ -782,10 +784,7 @@ func (s *ChatService) SendSystemMessage(roomID uint, content string) (*model.Cha
 			return err
 		}
 		return tx.Model(&model.ChatRoom{}).Where("id = ?", roomID).
-			Updates(map[string]interface{}{
-				"last_message_id": msg.ID,
-				"updated_at":      time.Now(),
-			}).Error
+			Update("updated_at", time.Now()).Error
 	})
 	if err != nil {
 		return nil, err
@@ -1020,7 +1019,7 @@ func (s *ChatService) SendMessage(senderID, roomID uint, content string, replyTo
 	if err != nil {
 		return nil, nil, err
 	}
-	if err := s.db.Preload("Sender").First(msg, msg.ID).Error; err != nil {
+	if err := s.db.Preload("Sender").Preload("Sender.Badges.Badge").First(msg, msg.ID).Error; err != nil {
 		return nil, nil, err
 	}
 	for _, uid := range mentionIDs {
@@ -1109,7 +1108,8 @@ func (s *ChatService) ListMessages(userID, roomID, beforeID uint, size int, over
 		q = q.Where("id < ?", beforeID)
 	}
 	var msgs []model.ChatMessage
-	if err := q.Order("id DESC").Limit(size + 1).Preload("Sender").Preload("Recaller").Find(&msgs).Error; err != nil {
+	// Sender.Badges.Badge 嵌套预加载：消息气泡需展示发送者等级与徽章（与成员列表一致）
+	if err := q.Order("id DESC").Limit(size + 1).Preload("Sender").Preload("Sender.Badges.Badge").Preload("Recaller").Find(&msgs).Error; err != nil {
 		return nil, false, err
 	}
 	hasMore := len(msgs) > size
@@ -1138,7 +1138,7 @@ func (s *ChatService) RecallMessage(operatorID, roomID, messageID uint, oversee
 		return nil, false, err
 	}
 	var msg model.ChatMessage
-	if err := s.db.Where("id = ? AND room_id = ?", messageID, roomID).First(&msg).Error; err != nil {
+	if err := s.db.Where("id = ? AND room_id = ?", messageID, roomID).Preload("Sender").First(&msg).Error; err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
 			return nil, false, ErrChatMsgNotFound
 		}
@@ -1147,6 +1147,10 @@ func (s *ChatService) RecallMessage(operatorID, roomID, messageID uint, oversee
 	if msg.RecalledAt != nil {
 		return &msg, false, nil // 幂等
 	}
+	// 站长的消息禁止群主/群管/站点消息管撤回（仅全站监管可撤回）
+	if msg.Sender.Role == model.RoleOwner && !oversee {
+		return nil, false, ErrChatRecallDenied
+	}
 	if msg.SenderID == operatorID {
 		if !oversee {
 			if _, err := s.membership(s.db, roomID, operatorID); err != nil {
@@ -1165,7 +1169,17 @@ func (s *ChatService) RecallMessage(operatorID, roomID, messageID uint, oversee
 	}
 	msg.RecalledAt = &now
 	msg.RecalledBy = operatorID
-	_ = s.db.Preload("Sender").Preload("Recaller").First(&msg, msg.ID)
+	// 撤回的是房间当前预览消息时，回退 last_message_id 到最近一条未撤回的非系统消息：
+	// 撤回不在会话列表留下「已撤回」预览，也不让房间因此停留在列表前排，避免被当成新消息提醒。
+	var prevID uint
+	_ = s.db.Model(&model.ChatMessage{}).
+		Where("room_id = ? AND deleted_at IS NULL AND recalled_at IS NULL AND is_system = ?", roomID, false).
+		Order("id DESC").Limit(1).
+		Select("id").Row().Scan(&prevID)
+	_ = s.db.Model(&model.ChatRoom{}).
+		Where("id = ? AND last_message_id = ?", roomID, msg.ID).
+		Update("last_message_id", prevID).Error
+	_ = s.db.Preload("Sender").Preload("Sender.Badges.Badge").Preload("Recaller").First(&msg, msg.ID)
 	return &msg, true, nil
 }
 
@@ -1345,13 +1359,13 @@ func (s *ChatService) MarkRead(userID, roomID, messageID uint) error {
 		Update("last_read_message_id", messageID).Error
 }
 
-// UnreadSummary 当前用户所有群的未读明细与总数
+// UnreadSummary 当前用户所有群的未读明细与总数（系统提示消息不计入）
 func (s *ChatService) UnreadSummary(userID uint) (int64, []UnreadRoom, error) {
 	var rows []UnreadRoom
 	err := s.db.Table("chat_messages AS m").
 		Select("m.room_id AS room_id, count(*) AS cnt").
 		Joins("JOIN chat_room_members AS rm ON rm.room_id = m.room_id AND rm.user_id = ?", userID).
-		Where("m.id > rm.last_read_message_id AND m.sender_id <> ? AND m.deleted_at IS NULL AND m.recalled_at IS NULL", userID).
+		Where("m.id > rm.last_read_message_id AND m.sender_id <> ? AND m.deleted_at IS NULL AND m.recalled_at IS NULL AND m.is_system = ?", userID, false).
 		Group("m.room_id").
 		Scan(&rows).Error
 	if err != nil {