chore: import upstream snapshot with attribution

tests/test_tools/test_node_runtime_stubs.py

@@ -0,0 +1,18 @@
+from __future__ import annotations
+
+import pytest
+
+from opensquilla.tools.builtin.nodes import canvas, nodes
+from opensquilla.tools.types import ToolError
+
+
+@pytest.mark.asyncio
+async def test_nodes_list_stub_reports_runtime_unavailable() -> None:
+    with pytest.raises(ToolError, match="configured node runtime"):
+        await nodes("list")
+
+
+@pytest.mark.asyncio
+async def test_canvas_stub_reports_runtime_unavailable() -> None:
+    with pytest.raises(ToolError, match="configured node runtime"):
+        await canvas("snapshot", "main")