fix: blocklist提前到消息处理最前端 — 拦截消息不浪费任何资源

- 移到 logging/enrichment/routing 之前
- 被拦截消息只记一条 [blocked] 日志，不调ai-core
- 时间戳/群名/昵称等富化处理不再对blocked消息执行

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

backend/platform-bridge/cmd/main.go

@@ -71,7 +71,32 @@ func main() {
 
 	// Set message handler with logging.
 	router.SetMessageHandler(func(msg *bridge.UnifiedMessage) (*bridge.UnifiedResponse, error) {
-		// Log incoming.
+		// Routing decisions.
+		isAdmin := mapper.IsAdmin(msg.Platform, msg.OriginalSenderUID)
+
+		// Blocklist check — MUST run first, before logging/enrichment,
+		// to avoid wasting resources on blocked users/groups.
+		if blocked := blocklistStore.IsBlocked(msg.ChannelType, msg.ChannelID, msg.OriginalSenderUID, isAdmin); blocked {
+			msgLogger.Log(logging.LogEntry{
+				Timestamp:  time.Now(),
+				Direction:  "incoming",
+				Platform:   msg.Platform,
+				ChannelID:  msg.ChannelID,
+				SenderID:   msg.OriginalSenderUID,
+				SenderName: msg.OriginalSenderName,
+				GroupName:  msg.GroupName,
+				Content:    "[blocked]",
+				Success:    true,
+			})
+			return &bridge.UnifiedResponse{
+				Messages: []bridge.ResponseMessage{
+					{DisplayType: "silent", Content: "", FormatMode: "plain"},
+				},
+				Platform: msg.Platform,
+			}, nil
+		}
+
+		// Log incoming (only non-blocked messages).
 		msgLogger.Log(logging.LogEntry{
 			Timestamp:   time.Now(),
 			Direction:   "incoming",
@@ -85,9 +110,6 @@ func main() {
 			MessageID:   msg.MessageID,
 			Success:     true,
 		})
-
-		// Routing decisions.
-		isAdmin := mapper.IsAdmin(msg.Platform, msg.OriginalSenderUID)
 		adminNick := cfg.AdminNickname
 		if isAdmin {
 			if id := mapper.ResolveOrNil(msg.Platform, msg.OriginalSenderUID); id != nil && id.Nickname != "" {
@@ -138,25 +160,6 @@ func main() {
 			msg.Content = fmt.Sprintf("【私聊 %s】%s/%s (%s)：\n%s", msg.Platform, adminNick, msg.OriginalSenderName, msg.OriginalSenderUID, msg.Content)
 		}
 
-		// Blocklist/whitelist check (admin always bypasses).
-		if blocked := blocklistStore.IsBlocked(msg.ChannelType, msg.ChannelID, msg.OriginalSenderUID, isAdmin); blocked {
-			msgLogger.Log(logging.LogEntry{
-				Timestamp:  time.Now(),
-				Direction:  "outgoing",
-				Platform:   msg.Platform,
-				ChannelID:  msg.ChannelID,
-				SenderID:   msg.OriginalSenderUID,
-				SenderName: "Cyrene",
-				Content:    "[blocked]",
-				Success:    true,
-			})
-			return &bridge.UnifiedResponse{
-				Messages: []bridge.ResponseMessage{
-					{DisplayType: "silent", Content: "", FormatMode: "plain"},
-				},
-				Platform: msg.Platform,
-			}, nil
-		}
 
 		var response *bridge.UnifiedResponse
 		var routeErr error