Use isa operator in cloud ndiquery live tests

The cloud search API no longer exposes document_class.class_name as a
directly searchable field path. Class filtering now has to go through
the 'isa' operator, which also rolls up subclasses. This was causing
test_ndiqueryAll_paginates to return zero documents against the live
server.

Only the two cloud ndiquery tests are affected. Inline document bodies
(e.g. {"document_class": {"class_name": "..."}}) and local
session.database_search calls continue to use the field directly since
they are not cloud search structures.

Author: claude

tests/test_cloud_live.py

@@ -794,13 +794,9 @@ def test_ndiquery_public(self, client):
         """ndiquery should return documents matching a search."""
         from ndi.cloud.api.documents import ndiquery
 
-        search = [
-            {
-                "field": "document_class.class_name",
-                "operation": "exact_string",
-                "param1": "session",
-            }
-        ]
+        # Class filtering on the cloud must go through the 'isa' operator;
+        # the document_class.class_name field path is no longer searchable.
+        search = [{"field": "", "operation": "isa", "param1": "session"}]
         result = _retry_on_server_error(
             lambda: ndiquery("public", search, page=1, page_size=5, client=client)
         )
@@ -828,13 +824,9 @@ def test_ndiqueryAll_paginates(self, client):
         """ndiqueryAll should auto-paginate results."""
         from ndi.cloud.api.documents import ndiqueryAll
 
-        search = [
-            {
-                "field": "document_class.class_name",
-                "operation": "exact_string",
-                "param1": "session",
-            }
-        ]
+        # Class filtering on the cloud must go through the 'isa' operator;
+        # the document_class.class_name field path is no longer searchable.
+        search = [{"field": "", "operation": "isa", "param1": "session"}]
         result = _retry_on_server_error(
             lambda: ndiqueryAll("public", search, page_size=3, client=client)
         )