fix(plugin): preserve response hook command context

[saltbo]

Summary

• invoke response-middleware plugins with the command context instead of the bounded response-body context
• preserve command cancellation without canceling middleware when a bounded response body closes
• cover timed responses with a response-middleware integration test

Behavior

Response-middleware hooks no longer fail with context canceled after a successful bounded response when --rsh-timeout is set.

Verification

• CGO_ENABLED=1 go test ./...
• CGO_ENABLED=1 go test -tags=integration ./...