Refactor HTTP body consumption
Summary
Added streaming variants for endpoints that download raw HTTP bodies so callers can stream responses directly to an io.Writer and avoid allocating memory for the entire response.
Key Changes
Added streaming methods that accept an io.Writer for memory-heavy endpoints. Each Stream* method builds the request and calls Client.Do(req, w) directly so the HTTP response body is copied into the previous writer without first buffering it. The only files touched are the ones where raw downloads live.
Related Issue
Closes #2134