feat(map): add batch export and adjust layout alignment

- Implement synchronous offscreen wafer map PNG rendering and CSV summary.
- Add "Batch Export" button to file browser sidebar.
- Adjust trend pane bottom spacer to align with About button when visible.
- Fix type check errors and add pytest coverage for batch export.

tests/test_device_controller.py

@@ -233,3 +233,12 @@ def test_device_service_port_caching(controller):
         service.enumerate_ports()
         assert mock_run.call_count == 2
 
+
+
+def test_export_dir_created_under_save_data_dir(controller):
+    from pathlib import Path
+
+    result = controller.exportDir()
+
+    assert result == str(Path(controller.saveDataDir) / "Export")
+    assert Path(result).is_dir()