fix(kg): resolve 'unhashable type: Entity' in GraphAnalyzer #159

- Robust ID extraction in CentralityCalculator, CommunityDetector, and ConnectivityAnalyzer
- Support for direct Entity objects and dictionaries as node identifiers
- Improved Entity hashability in utils/types.py
- Added integration test to verify fix and prevent regression

tests/test_export_methods_wrapper.py

@@ -0,0 +1,37 @@
+import sys
+import os
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
+
+import unittest
+import tempfile
+import shutil
+import yaml
+from pathlib import Path
+from semantica.export.methods import export_yaml
+
+class TestExportMethodsWrapper(unittest.TestCase):
+    def setUp(self):
+        self.test_dir = tempfile.mkdtemp()
+        self.schema = {
+            "uri": "http://example.org/schema",
+            "classes": [{"id": "Person", "label": "Person"}],
+            "properties": [{"id": "knows", "label": "Knows"}]
+        }
+
+    def tearDown(self):
+        shutil.rmtree(self.test_dir)
+
+    def test_export_yaml_schema(self):
+        output_path = Path(self.test_dir) / "schema.yaml"
+        
+        # This should call export_ontology_schema internally
+        export_yaml(self.schema, str(output_path), method="schema")
+        
+        self.assertTrue(output_path.exists())
+        with open(output_path, 'r') as f:
+            data = yaml.safe_load(f)
+            self.assertEqual(data['ontology']['uri'], "http://example.org/schema")
+            self.assertEqual(len(data['classes']), 1)
+
+if __name__ == '__main__':
+    unittest.main()