not sure that what AssignPet function use for?
and iirc there're Delete Upload and AssignPet that have to implement in image service right?

image.Upload(): uploads to S3 and create a row with url of that S3 (empty foreign key)
If upload has field petId, then petId will be filled (meaning image is created and assigned a pet at the same time)

image.AssignPet(): assigns row with specified url with that pet id (add foreign key)
image.Delete(): deletes row and object in S3

—--------------------------------
When creating pet,
For image upload, POST it, and keep the imageId from response
imageSrv.Upload(file) returns URL + imageId

For pet create, attach images’ urls into the POST request
petSrv.Create(pet + imageIds) => image.AssignPet(imageIds, petId)

—--------------------------------
When updating pet,
If delete image -> imageSrv removes the row with ID == image.id, bucket also deletes (image id got from FindByPetId fetched by client)
If upload image -> imageSrv.Upload()

Image svc in File repo is already done,
Pet svc in Backend repo still needs to use real image svc (currently they are empty [ ])
For gateway, make 3 endpoints for upload, assignpet and delete