The generic payment process page (linked from waiver "الانتقال إلى السداد") was
recording payments in the payments table but never updating the source records
(subscriptions.paid_amount, fines.paid_amount, installment_schedule.paid_amount).
This caused the debt check to keep showing debts as unpaid after payment.

Added handleSubscriptionPayment, handleFinePayment, and handleInstallmentPayment
methods that mark the underlying records as paid (oldest first).

Also fixed waiver debt check using wrong fines status ('pending' instead of
'imposed'/'appeal_upheld') which is what fines actually use.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>