fix: use correct key name for ChainedInvokeDetails deserialization

- Change key from snake_case "chained_invoke_details" to PascalCase
  "ChainedInvokeDetails" in Operation.from_dict() to match API response
- Add missing assertions in test_operation_from_dict_complete to verify
  chained_invoke_details is properly deserialized

Fixes #237

Author: alessandrobologna

src/aws_durable_execution_sdk_python/lambda_service.py

@@ -749,7 +749,7 @@ def from_dict(cls, data: MutableMapping[str, Any]) -> Operation:
             callback_details = CallbackDetails.from_dict(callback_details_input)
 
         chained_invoke_details = None
-        if chained_invoke_details := data.get("chained_invoke_details"):
+        if chained_invoke_details := data.get("ChainedInvokeDetails"):
             chained_invoke_details = ChainedInvokeDetails.from_dict(
                 chained_invoke_details
             )

tests/lambda_service_test.py

@@ -1481,6 +1481,8 @@ def test_operation_from_dict_complete():
     assert operation.step_details.result == "step_result"
     assert operation.wait_details.scheduled_end_timestamp == start_time
     assert operation.callback_details.callback_id == "cb1"
+    assert operation.chained_invoke_details is not None
+    assert operation.chained_invoke_details.result == "invoke_result"
 
 
 def test_operation_to_dict_with_subtype():