Revise ABLE Act definitions to conform to Montana individual income tax code

This bill updates the Montana Achieving a Better Life Experience (ABLE) Act by aligning its definitions with the federal Internal Revenue Code and the state's individual income tax code. It directly affects individuals with disabilities and their families who use ABLE accounts to save for qualified disability expenses. The key provision revises Section 53-25-103 of the Montana Code Annotated to ensure terms like "eligible individual," "qualified disability expenses," and "annual contribution limit" match federal standards. The changes take effect immediately and apply retroactively to tax years beginning after December 31, 2024.