Endpoint studies/{study} missing filename in the response

The studies/{study} response is missing the filename.

Response example:

Specification: https://dsjapi.net/docs#/default/study_studies__studyOID__get

Open the studies/{study} endpoint specification at https://dsjapi.net/docs#/default/study_studies__studyOID__get and compare its documented response with the example in the issue. Identify where the response schema is defined, then confirm that the response includes a filename and update the specification or implementation accordingly.

Written by the indexing model from the issue text.