Receivables summary cards (overdue / dueSoon / current / outstanding)

DARK — 404s unless ar_ap_items_enabled. Each figure is {amountCents, count} over OUTSTANDING balances (amount - paid) of items whose status is not paid/void/uncollectible. overdue = past due; dueSoon = due within 7 days; current = outstanding - overdue (identity holds for both amount and count). The aggregate carries currency and minorUnitExponent; an empty zero-value aggregate carries null/null rather than a guessed currency.