- Split profile_handlers.go into profile_handlers_core.go, profile_handlers_management_core.go, and profile_handlers_management_delete.go
- Simplify OrderProfileHandlerWithRepo with ICCID/IMSI-only validation and "downloaded" state
- Remove webhook and message queue notifications from order handler
- Add UpdateProfileHandler with state validation for downloaded/activated/deactivated/expired
- Add DeleteProfileHandler with existence
- Add DefaultManagerConfig with 30s health checks, 3 retries, and circuit breaker configuration
- Add CarrierConfig struct with ES2 settings, MCC/MNC, priority, and feature support
- Add ToCarrier method converting CarrierConfig to Carrier with metrics and capabilities
- Add HealthChecker with periodic carrier health monitoring and status evaluation
- Add LoadBalancer with weighted round-robin, least