[sahiljhawar]

Summary

DataSet can now load saved files that contain variables which are not part of the current data standard. Previously this raised AttributeError: Cannot set attribute '...'. It is not part of the saving strategy, so a file written by a branch with an extended (or older, renamed) standard could not be loaded from another branch. Such variables are now attached to the dataset and a warning is logged.

Feature / enhancement

• Feature: tolerate unknown variables when loading saved files.

Design notes

• Only the load path in DataSet._load_variable changed. Unknown names are set with object.__setattr__ and a logger.warning.
• __setattr__ is untouched, so user-set typos like ds.typo = 1 still raise.

Checklist

• SPDX headers already present on changed files.
• ruff check / ruff format clean.
• Test added (test_variable_missing_from_standard_is_loaded_with_warning, marked basic); tests/unittests/dataset passes.
• Backwards compatible: only turns a previous error into a warning.