Fix stdout/stderr ordering in ShutdownPrepCheck

Command::output() captures stdout and stderr as two separate
buffers. check() was concatenating stdout-then-stderr, which throws
away chronological order entirely -- every stderr line (e.g.
"Error: send_to_host not set" from `claw-store replicate` on a node
with no downstream replication target, which is normal and expected
on architect) landed at the very end of the report regardless of
when it actually printed, making a mid-script, already-handled
condition look like a failure that happened after "DRY RUN
COMPLETE".

Fix: invoke via `bash -c "script --dry-run 2>&1"` so stderr merges
into stdout inside the shell, before either stream reaches us --
true chronological order preserved, single buffer to read.

Verified on architect: the send_to_host message now appears exactly
where it happens, inside the "taking final snapshot + replicating"
step, with DRY RUN COMPLETE correctly last.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

claw-store/src/cluster/shutdown_prep.rs

@@ -87,16 +87,24 @@ pub async fn check() -> Result<ShutdownPrepCheckReply> {
     if !script.exists() {
         bail!("shutdown-prep script not found at {}", script.display());
     }
+    // `2>&1` inside the shell merges stderr into stdout *before*
+    // either stream is piped back to us, preserving true
+    // chronological order. Capturing stdout/stderr separately (as
+    // `Command::output()` does by default) and concatenating them
+    // after the fact loses interleaving entirely — every stderr line
+    // lands at the very end regardless of when it was actually
+    // printed, which makes a mid-script warning (e.g. "replicate not
+    // configured on this node") look like a failure that happened
+    // after "DRY RUN COMPLETE".
     let run = Command::new("bash")
-        .arg(&script)
-        .arg("--dry-run")
+        .arg("-c")
+        .arg(format!("{} --dry-run 2>&1", script.display()))
         .output();
     let output = timeout(CHECK_TIMEOUT, run)
         .await
         .context("shutdown-prep --dry-run timed out")?
         .context("spawning shutdown-prep --dry-run")?;
-    let mut combined = String::from_utf8_lossy(&output.stdout).into_owned();
-    combined.push_str(&String::from_utf8_lossy(&output.stderr));
+    let combined = String::from_utf8_lossy(&output.stdout).into_owned();
     Ok(ShutdownPrepCheckReply {
         ready: output.status.success(),
         output: combined,