When a subscription year is marked as paid, the member row's paid_amount
must include the 35 EGP dev fee (single flat charge per family). Previously
only total_amount + fine_amount was stored, causing remaining balance to
show dev fee as unpaid despite full payment.

Fixes: SubscriptionController::payYear(), RetroactiveMembershipService
(both createRetroactiveSubscription and processRetroactiveRenewal).
Migration Phase_92_006 corrects existing paid rows in the database.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>