feat(validation): export validation module from package

src/macro_lactone_toolkit/__init__.py

@@ -36,8 +36,10 @@ __all__ = [
     "MacrolactoneDetectionError",
     "MacrolactoneError",
     "MacrolactoneFragmenter",
+    "MacrolactoneValidator",
     "MacrocycleClassificationResult",
     "numbered_molecule_svg",
+    "ParentMolecule",
     "RingNumberingError",
     "RingNumberingResult",
     "results_to_dataframe",
@@ -48,4 +50,11 @@ __all__ = [
     "write_result_json",
 ]
 
+# Validation module (optional import)
+try:
+    from .validation.validator import MacrolactoneValidator
+    from .validation.models import ParentMolecule, SideChainFragment
+except ImportError:
+    pass  # SQLModel not installed
+
 __version__ = "0.1.0"