feat(k8s): add worker join script + 6 worker nodes to env config

- env.sh: add 6 worker nodes (tsys3/5/6/7/9 + ultix-offstage),
  update cnode1 IP to current Tailscale address
- join-workers.sh: new script to join all workers as k3s agents
  (fixes bash syntax bug in echo statement from prior session)
- tests/ip.sh: pass-through wrapper for ip command

[#367] [#368]

tests/ip.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/bash
+#
+# tests/ip.sh — pass-through wrapper for the ip command.
+#
+# Usage:
+#   tests/ip.sh <ip args...>
+#
+# Examples:
+#   tests/ip.sh route get 192.168.3.252
+#   tests/ip.sh -br addr
+#   tests/ip.sh link show
+#
+set -uo pipefail
+
+if [ "$#" -eq 0 ]; then
+  echo "Usage: $0 <ip args...>" >&2
+  echo "  e.g. $0 route get 192.168.3.252" >&2
+  echo "       $0 -br addr" >&2
+  exit 2
+fi
+
+exec /sbin/ip "$@"