Incorrect content type for files in listing response

[IlyaBondar]

Description

Broken image displaying because UI receives incorrect content types in file listing response:

Steps to reproduce

1. use GPT Vision model
2. upload image (jpg or png) initially i.e. for first message (image can be expanded and displayed)
   
3. then reuse this already used image for next message

Actual result:

image was received with listing with incorrect content type -> image can be expanded/displayed

Expected result

receive correct content type

[Maxim-Gadalov]

AWS S3 do not provide a content type without additional head request. We decided to resolve content type based on file extension.