[feature] Factor assets and liability into impact calculation

[tinybigideas]

Feature Description

Right now, impact follows the formula:

impact = (item.income > 0
        ? income.value - item.income > expenditure.value
          ? fireReq.value / profit.value -
            fireReq.value / (income.value - item.income - expenditure.value)
          : -Infinity
        : fireReq.value / profit.value -
          (fireReq.value - (item.essential ? item.expenditure * 25 : 0)) /
            (item.expenditure + profit.value)

There's no reference to assets or liability. However, a mortgage is a liability and an asset depending on your interpretation. However, implementing any idea of liability or assets here would potentially over-complicate this metric.

Use Case

Is this useful? Not sure. It'll "help" your FIRE number by reducing impact of items such as a mortgage which has no income, large liability, and potentially large asset value.