- Fix Bug A: RunRemote was re-prefixing destination with user@host: when
engine.go:135 already pre-prefixed it for remote-to-remote, causing
"admin@host:admin@host:/path" to be passed to rsync
- Fix Bug B: Run used args[1:] when inserting -e ssh, silently dropping
the first rsync flag (e.g. -aP became flag-less)
- Fix Bug C: RunRemote extracted source/dest in wrong order for pull
direction (buildArgs reverses them but RunRemote assumed push order)
- Add rsync_runner_test.go covering buildArgs, RunRemote prefixing,
and flag preservation
