Use this when you need to project a principal's growth under compound interest, optionally with recurring monthly contributions, returning the final balance and a year-by-year breakdown rather than estimating compound growth yourself.

Use this when you need to project a principal's growth under compound interest, optionally with recurring monthly contributions, returning the final balance and a year-by-year breakdown rather than estimating compound growth yourself. Iterates month-by-month for accuracy; contributions are added at the start of each month; compoundingPerYear defaults to 12. annualRate is a percent; years is 1-200. Deterministic: same input, same output. Example: principal 10000, annualRate 7, years 10, monthlyContribution 500 -> finalBalance 107143.85, totalContributions 70000, totalInterest 37143.85, with a 10-row schedule (one per year).