fix(arbo): python-based healthcheck (slim image ships no curl/wget)

stacks/arbo/compose.yaml

@@ -59,8 +59,9 @@ services:
       # catalog checkout (comfy-dev clone on the host), read-only:
       - ${ARBO_CATALOG_DIR:-/worktank/arbo/repo}/catalog:/app/catalog:ro    # CONFIRM in-container path vs image layout
       - ${ARBO_CATALOG_DIR:-/worktank/arbo/repo}/graphs:/app/graphs:ro      # CONFIRM in-container path vs image layout
+    # python-based (the slim image ships no curl/wget; python is always present):
     healthcheck:
-      test: ["CMD-SHELL", "curl -fsS http://localhost:8200/healthz >/dev/null || exit 1"]
+      test: ["CMD-SHELL", "python -c \"import urllib.request,sys; sys.exit(0 if urllib.request.urlopen('http://localhost:8200/healthz').status==200 else 1)\""]
       interval: 30s
       timeout: 10s
       retries: 3