## New Files

### Core.Eventing
- IExternalEventSubscriber.cs - Base interface for event subscribers
- ExternalEventSubscriberOptions.cs - Base options class

### Core.Eventing.Azure
- ServiceBusEventSubscriber.cs - Azure Service Bus subscriber
- ServiceBusEventSubscriberOptions.cs

### Core.Eventing.AWS
- SqsEventSubscriber.cs - AWS SQS subscriber (for SNS→SQS pattern)
- SqsEventSubscriberOptions.cs

### Core.Eventing.RabbitMQ
- RabbitMqEventSubscriber.cs - RabbitMQ subscriber
- RabbitMqEventSubscriberOptions.cs

## DI Extensions
- AddAzureServiceBusSubscriber()
- AddAwsSqsSubscriber()
- AddRabbitMqSubscriber()

All subscribers include HostedService wrappers for automatic lifecycle management.