chore: remove imageunderstand redundant code (#682)

backend/infra/contract/document/imageunderstand/imageunderstand.go

@@ -1,23 +0,0 @@
-/*
- * Copyright 2025 coze-dev Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package imageunderstand
-
-import "context"
-
-type ImageUnderstand interface {
-	ImageUnderstand(ctx context.Context, image []byte) (content string, err error)
-}