- Create app/nodes.py with _CONFIG_DIR testability seam, _load_config,
_profiles_dir, _profile_path, _load_profile, _get_ollama_url helpers,
and stub list_nodes endpoint returning [] when no coordinator_url is set
- Mount nodes router at /api/nodes-mgmt in app/api.py
- Add profiles_dir comment to config/label_tool.yaml.example cforch section
- Create tests/test_nodes.py with autouse fixture and two passing tests
