Refactor DataSource classes and enhance testing framework

- Removed outdated comments and documentation from CsvSessionSource and DemoSource classes.
- Introduced new unit tests for CsvSource and DataSource functionalities, ensuring robust validation of CSV loading and session handling.
- Added UI smoke tests to verify window instantiation and menu actions without hardware dependencies.
- Implemented VisionEngine tests to validate demo snapshots and alignment state logic.

tests/test_ui_smoke.py

@@ -0,0 +1,58 @@
+from __future__ import annotations
+
+import unittest
+
+
+try:
+    from PySide6 import QtWidgets
+
+    PYSIDE6_IMPORT_ERROR = None
+except Exception as exc:  
+    QtWidgets = None
+    PYSIDE6_IMPORT_ERROR = exc
+
+
+@unittest.skipIf(PYSIDE6_IMPORT_ERROR is not None, "PySide6 is not installed")
+class UiSmokeTests(unittest.TestCase):
+    def test_windows_instantiate_without_hardware(self) -> None:
+        from wafer_edge.App import UserWindow
+
+        app = QtWidgets.QApplication.instance() or QtWidgets.QApplication([])
+
+        user = UserWindow()
+
+        self.assertEqual(user.windowTitle(), "Wafer Position Monitor")
+        self.assertEqual(user.source_label.text(), "User App")
+        app.quit()
+
+    def test_file_menu_has_open_session_action(self) -> None:
+        """Verify File → Open Session… action exists in the menu bar."""
+        from wafer_edge.App import UserWindow
+
+        app = QtWidgets.QApplication.instance() or QtWidgets.QApplication([])
+
+        user = UserWindow()
+        menu_bar = user.menuBar()
+        self.assertIsNotNone(menu_bar)
+
+        file_menu = None
+        for action in menu_bar.actions():
+            menu = action.menu()
+            if menu is not None and menu.title() in ("File", "&File"):
+                file_menu = menu
+                break
+
+        self.assertIsNotNone(file_menu, "File menu should exist in the menu bar")
+
+        # Check that "Open Session…" is one of the menu actions.
+        action_texts = {a.text() for a in file_menu.actions()}
+        self.assertIn(
+            "Open Session…",
+            action_texts,
+            "File menu should contain an 'Open Session…' action",
+        )
+        app.quit()
+
+
+if __name__ == "__main__":
+    unittest.main()