fix(tests): cuDF compatibility for tolist() calls in chain optimization tests

Use to_arrow().to_pylist() for cuDF with fallback to tolist() for pandas.
Fixes test_same_nodes_with_and_without_where and test_same_edges_with_and_without_where.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: lmeyerov

tests/gfql/ref/test_chain_optimizations.py

@@ -920,8 +920,13 @@ def test_same_nodes_with_and_without_where(self, linear_graph):
         chain_with_where = Chain(ops, where=where)
         result_with_where = linear_graph.gfql(chain_with_where)
 
-        nodes_no_where = set(result_no_where._nodes['id'].tolist())
-        nodes_with_where = set(result_with_where._nodes['id'].tolist())
+        # Use to_arrow().to_pylist() for cuDF compatibility
+        try:
+            nodes_no_where = set(result_no_where._nodes['id'].to_arrow().to_pylist())
+            nodes_with_where = set(result_with_where._nodes['id'].to_arrow().to_pylist())
+        except AttributeError:
+            nodes_no_where = set(result_no_where._nodes['id'].tolist())
+            nodes_with_where = set(result_with_where._nodes['id'].tolist())
 
         assert nodes_no_where == nodes_with_where
 
@@ -939,8 +944,13 @@ def test_same_edges_with_and_without_where(self, linear_graph):
         chain_with_where = Chain(ops, where=where)
         result_with_where = linear_graph.gfql(chain_with_where)
 
-        edges_no_where = set(result_no_where._edges['eid'].tolist())
-        edges_with_where = set(result_with_where._edges['eid'].tolist())
+        # Use to_arrow().to_pylist() for cuDF compatibility
+        try:
+            edges_no_where = set(result_no_where._edges['eid'].to_arrow().to_pylist())
+            edges_with_where = set(result_with_where._edges['eid'].to_arrow().to_pylist())
+        except AttributeError:
+            edges_no_where = set(result_no_where._edges['eid'].tolist())
+            edges_with_where = set(result_with_where._edges['eid'].tolist())
 
         assert edges_no_where == edges_with_where