Add stability hardening and self-heal recovery

iso/builder/smoketest.sh

@@ -171,6 +171,12 @@ for svc in bee-nvidia bee-network bee-preflight bee-audit bee-web; do
     fi
 done
 
+if systemctl is-active --quiet bee-selfheal.timer 2>/dev/null; then
+    ok "timer active: bee-selfheal.timer"
+else
+    fail "timer NOT active: bee-selfheal.timer"
+fi
+
 echo ""
 echo "-- runtime health --"
 if [ -f /appdata/bee/export/runtime-health.json ] && [ -s /appdata/bee/export/runtime-health.json ]; then