Run one verified repayment projection

Computes the year-1 payment, payoff/forgiveness date, amount forgiven, forgiveness tax, total out-of-pocket and weighted-average rate for the supplied loans under one repayment plan. Calc-only; no stored client data is read or returned. Send "includeYearly": true to add yearly to each projection: year 0 is the loan book as sent; year n covers repayment months 12(n-1) to 12n-1 and gives the principal and interest balance after that year's last payment, the payments that year, the cumulative paid and any balance forgiven that year (date = that month). The series ends at the payoff or forgiveness month. Payments sum to totalOutOfPocket and forgiven amounts to amountForgiven. Money in cents. Default false: the field is then absent and the response is unchanged. A plan whose answer is an artifact of the prior-month count (nothing left to pay, the whole balance in one payment, or forgiveness before any payment) is a 400 naming the plan, the same plans the free calculator at /v1/calculators/loan leaves out.