refactor: simplify order status model — remove DELIVERY_FEE_ADJUSTMENT and PAYMENT_VERIFICATION

- Add deliveryFeeLocked field to Order model
- Remove DELIVERY_FEE_ADJUSTMENT and PAYMENT_VERIFICATION statuses (11→8)
- 3 order paths: delivery+online (locked→unlocked→paid), pickup+online (unlocked→paid), pickup+on_pickup (direct to in_progress)
- Update checkout to use PENDING_PAYMENT + deliveryFeeLocked
- Update payment flow to stay in PENDING_PAYMENT until admin confirms
- Update admin UI to use deliveryFeeLocked instead of status check
- Update client payment UI with new deliveryFeeLocked logic

server/prisma/schema.prisma

@@ -125,6 +125,7 @@ model Order {
   id                  String      @id @default(cuid())
   /// Статус заказа (валидация переходов на уровне API)
   status              String      @default("DRAFT")
+  deliveryFeeLocked   Boolean     @default(false)
   /// 'delivery' | 'pickup'
   deliveryType        String      @default("delivery")
   /// RUSSIAN_POST | OZON_PVZ | YANDEX_PVZ | FIVE_POST при deliveryType=delivery