fix: use docker stop only, no rm step

Containers with --rm (default) auto-remove on stop already.
Containers with --keep should stay after stop.
Previously the separate rm step either raced with --rm auto-removal
or forcefully removed --keep containers.

Stop is now graceful: docker stop only, no forced removal.

src/docker/mod.rs

@@ -191,7 +191,7 @@ pub async fn stop_cluster(
             config,
             node,
             format!(
-                "docker ps -qa --filter \"label=sm121.recipe={}\" | xargs -r docker rm -f",
+                "docker ps -q --filter \"label=sm121.recipe={}\" | xargs -r docker stop",
                 recipe_name
             ),
             dry_run,