- Update Service struct to use repository.Repository interface
- Update all method signatures to use repository package types (RatePlan, RatePlanSubscription, RatePlanUsage, etc.)
- Update filter and request types to use repository package (RatePlanFilter, SubscriptionFilter, CalculateCostRequest, etc.)
- Update status constants to use repository package (SubscriptionStatusActive, PlanStatusActive, DiscountTypePercentage, DiscountTypeFixed)
- Rename internal/service to internal/services in carrier-connector
- Update service imports in selection_integration.go and smdp_integration.go
- Move currency repository files from internal/currency to internal/repository
- Move rate plan repository files from internal/rateplan to internal/repository
- Update package declarations and imports for currency domain types
- Add currency package imports