Provide income based tax credit

This bill establishes a new income-based tax credit for Montana individual taxpayers with low-to-moderate income. It provides a credit equal to 4.7% of taxable income, but phases out completely when income exceeds specific thresholds ($2,000 for joint filers, $1,500 for heads of household, and $1,000 for other individual filers). The credit reduces tax liability but is unavailable for dependents, trusts, or taxpayers exceeding the phaseout income levels. The bill also requires the credit to be reviewed every eight years as part of Montana's broader tax credit review process.