v0.4.0

Breaking changes

• promote read_structure(...) as the primary public structure reader
• align the CLI on neutral structure input naming instead of restart-specific terminology
• reject XYZ plus multi-molecule moldescriptor combinations explicitly because XYZ files do not encode molecule-type assignments

Added

• add CLI test coverage for XYZ structure input
• document the structure-input model and 0.4.0 transition in CHANGELOG.md