deploy/ssh: return non-zero when a server deployment fails (#6795)

ssh_deploy() ignored the result of _ssh_deploy and always returned
success, so a failed transfer to one (or all) of the servers in
DEPLOY_SSH_SERVER was silently swallowed. Track the return code across
the loop and return non-zero if any server failed, letting the caller
handle notification.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

deploy/ssh.sh

@@ -170,10 +170,16 @@ ssh_deploy() {
     _info "Required commands batched and sent in single call to remote host"
   fi
 
+  _returnCode=0
   _deploy_ssh_servers="$DEPLOY_SSH_SERVER"
   for DEPLOY_SSH_SERVER in $_deploy_ssh_servers; do
-    _ssh_deploy
+    if ! _ssh_deploy; then
+      # in case of an error, remember it, but keep going for the remaining servers
+      _returnCode=1
+    fi
   done
+
+  return $_returnCode
 }
 
 _ssh_deploy() {