Implement real async COS image upload

src/test/resources/application.properties

@@ -6,6 +6,10 @@ spring.jpa.hibernate.ddl-auto=create-drop
 
 resend.api.key=dummy
 cos.base-url=http://test.example.com
+cos.secret-id=dummy
+cos.secret-key=dummy
+cos.region=ap-guangzhou
+cos.bucket-name=testbucket
 
 app.jwt.secret=TestSecret
 app.jwt.expiration=3600000