feat: [backend] vision support (#1510)

Co-authored-by: Garfield Dai <dai.hai@foxmail.com>

api/controllers/files/__init__.py

@@ -0,0 +1,10 @@
+# -*- coding:utf-8 -*-
+from flask import Blueprint
+
+from libs.external_api import ExternalApi
+
+bp = Blueprint('files', __name__)
+api = ExternalApi(bp)
+
+
+from . import image_preview