logCashPayment and linkPaymentToMember unconditionally set last_paid_at to the
(possibly backdated) transaction_date and forced payment_status='current', so
logging/linking a historical payment moved a member's dues state backward.
New pure resolveDuesAdvance() keeps the later of existing/incoming date and only
marks 'current' when the payment actually advances; both sites read the current
date first. Identical in the common (newest-payment) case.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>