* fix: cancel volume server requests on client disconnect during S3 downloads
- Use http.NewRequestWithContext in ReadUrlAsStream so in-flight volume
server requests are properly aborted when the client disconnects and
the request context is canceled
- Distinguish context-canceled errors (client disconnect, expected) from
real server errors in streamFromVolumeServers; log at V(3) instead of
ERROR to reduce noise from client-side disconnects (e.g. Nginx upstream
timeout, browser cancel, curl --max-time)
Fixes: streamFromVolumeServers: streamFn failed...context canceled"
* fixup: separate Canceled/DeadlineExceeded log severity in streamFromVolumeServers
- context.Canceled → V(3) Infof "client disconnected" (expected, no noise)
- context.DeadlineExceeded → Warningf "server-side deadline exceeded" (unexpected, needs attention)
- all other errors → Errorf (unchanged)"
38e14a867b