Business rule: مصاريف تنمية is a single flat 35 EGP fee per family per year,
NOT per person, NOT included in discountable base, added AFTER all calculations.

Changes:
- Generator: total_amount = base - discount (dev fee stored separately, not in total)
- Migration: subtracts dev_fee from total_amount for existing unpaid rows
- payYear(): adds single dev fee on top of subscription+fine totals at payment
- View: dev fee shown as separate line below the subscription subtotal, before
  the invoice grand total. Table columns simplified (no per-row dev fee column)

Calculation order:
1. Sum all family subscription bases
2. Apply year discount (e.g. 50% for 2023/2024) to subscription amounts
3. Add single 35 EGP dev fee as standalone charge at the end
4. Add fines (on subscription only, not dev fee)
= Final invoice total
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>