chore: import upstream snapshot with attribution

tests/resources/agents/async-tools/tools/python/boom_async.py

@@ -0,0 +1,16 @@
+"""boom_async fixture tool (always raises, to exercise the async failure path)."""
+
+from __future__ import annotations
+
+from omnigent_client.tools import tool
+
+
+@tool
+def boom_async() -> str:
+    """
+    Always raise so the failure path of the async pipeline is exercised.
+
+    :raises RuntimeError: Always, with message ``ASYNC_TOOL_BOOM_MARKER``.
+    :returns: Never returns normally.
+    """
+    raise RuntimeError("ASYNC_TOOL_BOOM_MARKER")