fix: remove redundant human support suggestion in fallback reply

internal/ai/runtime/executor/knowledge_guard.go

@@ -57,11 +57,7 @@ func resolveKnowledgeHumanSupportFallback(aiAgent models.AIAgent) string {
 	if strs.IsBlank(base) {
 		base = "当前知识库暂无明确信息。"
 	}
-	humanSupport := "建议你联系人工客服进一步确认。"
+	return base
-	if strings.Contains(base, humanSupport) {
-		return base
-	}
-	return base + " " + humanSupport
 }
 
 func buildKnowledgeRuntimeInstruction(answerMode enums.KnowledgeAnswerMode, fallbackReply string) string {