Add Duolingo API integration to backend

Слиты effective-dev-opensource запросил слияние feature/duolingo-backend-integration в develop

Created by: KrugarValdes

  • Created backend:feature:tv-modules package to group TV-related features
  • Introduced Duolingo module with REST endpoint for fetching user data
  • Created DTOs (LiveOpsFeatureDTO, DuolingoUserDTO, DuolingoResponseDTO, CurrentStreakDTO) for structured data handling
  • Implemented DuolingoService for API communication using WebClient
  • Added DuolingoController for handling HTTP requests
  • Configured WebClient in DuolingoConfig for Duolingo API connectivity
  • Updated Gradle configuration