Fix mutable default in configclass fallback (no-IsaacLab path)

[lanafi00]

Description

matterix_sm is supposed to work without Isaac Lab installed, using the fallback configclass in _compat.py. Right now it crashes on import because two fields use a mutable default (= []) instead of field(default_factory=list):

• primitive_actions/semantic_action.py
• primitive_actions/wait.py

The dataclasses module doesn't allow mutable defaults (Isaac Lab's own configclass apparently handles this, but the fallback doesn't). Fixed both to use default_factory, matching the pattern already used in semantic_info.py. Imported field from dataclasses in both files.

Tested that import matterix_sm works standalone after the fix (HAS_ISAACLAB=False).

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• I have run the pre-commit checks with <FULL_PATH_TO_ISAACLAB>/isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have updated the changelog and the corresponding version in the extension's config/extension.toml file
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[kouroshD]

Thanks, merged.