fix: 平台消息身份传递 — AI-Core 收到正确昵称而非永远 fallback 到管理员

- forwardToAICore 新增 nickname 字段，格式 "昵称 (QQ号)" 明确标识发送者
- 解决非管理员用户 @昔涟 时 AI 仍认为是管理员的身份污染问题
- 同时包含：管理员群聊插入抑制、markdown 粗体剥离、SearXNG 容器、ethend 窗口隐藏

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/platform-bridge/cmd/main.go

@@ -84,7 +84,7 @@ func main() {
 
 		// Routing decisions.
 		isAdmin := mapper.IsAdmin(msg.Platform, msg.OriginalSenderUID)
-		isMentioned, mentionReason := detectAdminMention(msg, mapper, cfg)
+		isMentioned, _ := detectAdminMention(msg, mapper, cfg)
 		isBotMentioned := msg.BotUID != "" && containsString(msg.Mentions, msg.BotUID)
 		isSilent := cfg.PlatformSilentEnabled && !isAdmin && !isBotMentioned
 
@@ -113,7 +113,6 @@ func main() {
 
 		// Extract image URLs for vision/OCR processing (admin + bot-mentioned + admin-mentioned only).
 		imageURLs := getImageURLs(msg)
-		includeImages := isAdmin || isBotMentioned || isMentioned
 
 		// For group chats, use a channel-based user ID to share context between admin and regular users.
 		chatUserID := msg.SenderID
@@ -123,6 +122,11 @@ func main() {
 		groupSessionID := fmt.Sprintf("platform_%s_%s", msg.Platform, msg.ChannelID)
 
 		switch {
+		case isAdmin && !isBotMentioned && shouldAdminBeSilent(msg, router):
+			msg.RouteType = "silent"
+			namespace := buildMemoryNamespace(msg.Platform, msg.ChannelType, msg.ChannelID)
+			response, routeErr = forwardToAICore(cfg, msg, "platform_silent", namespace, namespace, nil)
+
 		case isAdmin:
 			msg.RouteType = "normal"
 			response, routeErr = forwardToAICore(cfg, msg, "text", chatUserID, groupSessionID, imageURLs)
@@ -132,19 +136,11 @@ func main() {
 			response, routeErr = forwardToAICore(cfg, msg, "text", chatUserID, groupSessionID, imageURLs)
 
 		case isMentioned:
-			msg.RouteType = "admin_mention"
-			enhancedContent := fmt.Sprintf(
-				"[来自%s平台 %s 频道 %s 的用户 %s 说]\n%s\n\n[系统提示：此消息提及了管理员（原因：%s）。请参考以上消息内容判断是否需要关注。]",
-				msg.Platform, msg.ChannelType, msg.ChannelID, msg.SenderName, msg.Content, mentionReason,
-			)
-			originalContent := msg.Content
-			msg.Content = enhancedContent
-			if includeImages {
-				response, routeErr = forwardToAICore(cfg, msg, "text", "admin", "admin-session-main", imageURLs)
-			} else {
-				response, routeErr = forwardToAICore(cfg, msg, "text", "admin", "admin-session-main", nil)
-			}
-			msg.Content = originalContent
+			// Non-admin user mentioned an admin. Don't respond in channel —
+			// the admin already gets QQ's native @notification. Observe silently.
+			msg.RouteType = "silent"
+			namespace := buildMemoryNamespace(msg.Platform, msg.ChannelType, msg.ChannelID)
+			response, routeErr = forwardToAICore(cfg, msg, "platform_silent", namespace, namespace, nil)
 
 		case isSilent:
 			msg.RouteType = "silent"
@@ -191,7 +187,7 @@ func main() {
 					Direction:   "outgoing",
 					Platform:    msg.Platform,
 					ChannelID:   msg.ChannelID,
-					SenderID:    msg.OriginalSenderUID,
+					SenderID:    msg.BotUID,
 					SenderName:  "Cyrene",
 					Content:     rm.Content,
 					ContentType: "text",
@@ -493,6 +489,31 @@ func containsString(list []string, val string) bool {
 	return false
 }
 
+// shouldAdminBeSilent checks if admin is talking to other users in a group.
+// Returns true if 昔涟 should not interrupt (route as silent observation instead).
+func shouldAdminBeSilent(msg *bridge.UnifiedMessage, router *bridge.PlatformRouter) bool {
+	if msg.ChannelType != "group" {
+		return false
+	}
+	// Rule 1: Admin @mentions someone other than the bot → talking to them, don't interrupt.
+	for _, m := range msg.Mentions {
+		if m != msg.BotUID {
+			return true
+		}
+	}
+	// Rule 2: Recent context shows a conversation with non-admin users.
+	// Note: updateContext runs before this handler, so RecentSenders already
+	// includes the current message. Check the second-to-last sender instead.
+	ctx := router.GetContext(msg.Platform, msg.ChannelID)
+	if ctx != nil && len(ctx.RecentSenders) >= 2 {
+		prevSender := ctx.RecentSenders[len(ctx.RecentSenders)-2]
+		if prevSender != msg.OriginalSenderUID && prevSender != msg.BotUID {
+			return true
+		}
+	}
+	return false
+}
+
 // getImageURLs extracts image attachment URLs from a UnifiedMessage.
 func getImageURLs(msg *bridge.UnifiedMessage) []string {
 	if len(msg.Attachments) == 0 {
@@ -516,6 +537,7 @@ func forwardToAICore(cfg *config.Config, msg *bridge.UnifiedMessage, mode, userI
 		"message":    msg.Content,
 		"mode":       mode,
 		"routing":    msg.RouteType,
+		"nickname":   fmt.Sprintf("%s (%s)", msg.SenderName, msg.OriginalSenderUID),
 		"source": map[string]string{
 			"platform":      msg.Platform,
 			"channel_id":    msg.ChannelID,