perfsprint 18→0：strconv.Itoa/FormatInt/FormatUint/FormatBool 替代 fmt.Sprintf、无动词 fmt.Errorf→errors.New、纯字符串拼接。全部语义等价（已核对 diff）。修正 fixer 遗留的 import 问题（引入 goimports 统一整理）。

Result: {"status":"keep","total_issues":56,"golint_canonicalheader":8,"golint_errname":1,"golint_errorlint":12,"golint_forcetypeassert":3,"golint_gosec":0,"golint_intrange":3,"golint_modernize":5,"golint_nilnil":3,"golint_perfsprint":0,"golint_prealloc":3,"golint_recvcheck":7,"golint_usestdlibvars":3,"golint_wastedassign":7,"golint_total":55,"eslint_problems":1,"eslint_errors":0,"eslint_warnings":1,"tsc_errors":0,"measure_s":47}

internal/apps/user/tasks.go

@@ -152,7 +152,7 @@ func (h *SendEmailHandler) Execute(ctx context.Context, payload []byte) (*task.T
 		return nil, fmt.Errorf(errSendMailFailed, err)
 	}
 
-	msg := fmt.Sprintf("邮件成功发送至: %s", req.To)
+	msg := "邮件成功发送至: " + req.To
 	task.AppendLog(ctx, "%s", msg)
 
 	return &task.TaskResult{