Fix test discovery by adding __init__.py files

pytest.ini

@@ -3,7 +3,7 @@ testpaths = tests
 python_files = test_*.py
 python_classes = Test*
 python_functions = test_*
-addopts = -v --tb=short -n 4  # Limit to 4 parallel workers
+addopts = -v --tb=short -n 4 --import-mode=importlib
 markers =
     slow: marks tests as slow (deselect with '-m "not slow"')
     integration: marks tests as integration tests

src/__init__.py

@@ -0,0 +1,2 @@
+# This file is intentionally empty.
+# It marks the src directory as a Python package. 

tests/__init__.py

@@ -0,0 +1,2 @@
+# This file is intentionally empty.
+# It marks the tests directory as a Python package for test discovery.