feat(ui): improve device session management, update data directory paths, and add session clearing functionality.

src/pygui/backend/data/local_settings_model.py

@@ -52,7 +52,7 @@ class LocalSettingsModel(QObject):
             QStandardPaths.DocumentsLocation
         )
         base_dir = Path(documents_dir) if documents_dir else (Path.home() / "Documents")
-        return base_dir / "isc_data"
+        return base_dir / "ISC_DATA"
 
     def _new_defaults(self) -> dict[str, Any]:
         return {