refactor(subscription): Break down AbonnementActuel into reusable components and add extra questions purchase feature

- Refactor monolithic AbonnementActuel component into smaller, focused components:
  • ErrorState: Centralized error handling with retry functionality
  • PaymentMethodCard: Standalone payment method display
  • SubscriptionCard: Enhanced card with status badges and pricing
  • SubscriptionFeatures: Modular features list component
  • SubscriptionActions: Reusable action buttons component
  • ExplorePlansCard: Promotional card for plan exploration

- Add new ExtraPurchaseCard component with:
  • Quick-buy options (50, 100, 200, 500 questions)
  • Custom quantity input with real-time validation
  • Volume discounts (10% off for 200+ questions)
  • Dynamic pricing breakdown with savings display
  • Animated UI with smooth expand/collapse transitions