ci(e2e-nightly): dump cluster journals on failure (mulga-siv-32)

run-multinode-e2e.sh dumps node journals via its own EXIT trap, but
run-cert-e2e.sh / run-lb-e2e.sh / reboot-e2e do not. When those scripts
fail the cluster is destroyed in Teardown without surfacing any daemon
logs, blocking root-cause analysis.

Add a workflow step that runs after the test scripts but before
Teardown when a previous step failed, ssh'ing to each node and pulling
the last 200 lines of every spinifex-* unit. Best-effort: skips
gracefully when inventory or nodes are unreachable.

Diagnostic-only; no behavioural change to the test path.

.github/workflows/e2e-nightly.yml

@@ -196,6 +196,24 @@ jobs:
 
           WAN_IP="$WAN_IP" SSH_KEY="$SSH_KEY" "$REBOOT_DIR/run-reboot-e2e.sh"
 
+      - name: Dump Cluster Journals on Failure
+        if: failure() && steps.gate.outputs.selected == 'true'
+        working-directory: mulga/scripts/tofu-cluster
+        run: |
+          INVENTORY=$(tofu output -json inventory 2>/dev/null) || { echo "no inventory; skipping"; exit 0; }
+          SSH_KEY=$(echo "$INVENTORY" | jq -r '.ssh_key_path')
+          SSH_KEY="${SSH_KEY/#\~/$HOME}"
+          NODE_COUNT=$(echo "$INVENTORY" | jq '.nodes | length')
+          for i in $(seq 0 $((NODE_COUNT - 1))); do
+            IP=$(echo "$INVENTORY" | jq -r ".nodes[$i].wan_ip")
+            echo "===== node$((i+1)) ($IP) ====="
+            for svc in spinifex-nats spinifex-predastore spinifex-viperblock spinifex-daemon spinifex-awsgw spinifex-vpcd; do
+              echo "--- $svc ---"
+              ssh -o StrictHostKeyChecking=no -o ConnectTimeout=5 -i "$SSH_KEY" tf-user@${IP} \
+                "sudo journalctl -u $svc --no-pager -n 200 2>/dev/null || echo '(not found)'" 2>&1 || echo "(node unreachable)"
+            done
+          done
+
       - name: Teardown
         if: always()
         working-directory: mulga/scripts/tofu-cluster