feat: RabbitMQ outbox transport (`NetEvolve.Pulse.RabbitMQ`)

[samtrion]

User Story

As a developer using RabbitMQ as a message broker, I want a native RabbitMQ transport for the outbox processor, so that I can deliver outbox messages to RabbitMQ exchanges without routing them through Dapr.

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Background

RabbitMQ is a widely adopted on-premise and cloud-agnostic message broker. Teams using RabbitMQ directly (without Dapr) need a first-class transport integration that uses the official .NET client.

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Requirements

• Provide a new NuGet package NetEvolve.Pulse.RabbitMQ targeting net8.0, net9.0, net10.0.
• Implement RabbitMqMessageTransport : IMessageTransport using RabbitMQ.Client (v7+, async API).
• Support the following capabilities:
  • SendAsync — publishes a single message to a preconfigured exchange with a routing key.
  • SendBatchAsync — publishes multiple messages in a single channel write.
  • IsHealthyAsync — verifies the connection/channel is open and the broker is reachable.
• Configurable via RabbitMqTransportOptions:
  • HostName, Port, VirtualHost, UserName, Password.
  • ExchangeName — target exchange.
  • RoutingKey — default routing key (can be overridden per event type via a resolver delegate).
• Expose registration via IMediatorConfigurator:

  services.AddPulse(c => c.UseRabbitMqTransport(options => { ... }));

• The package must reference RabbitMQ.Client and NetEvolve.Pulse.Extensibility.

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Acceptance Criteria

• NetEvolve.Pulse.RabbitMQ package builds on all three target frameworks.
• SendAsync publishes a correctly serialized message to the configured exchange.
• SendBatchAsync publishes all messages without opening multiple connections.
• IsHealthyAsync returns false without throwing when the broker is unreachable.
• Connection/channel lifecycle is managed correctly (reconnect on failure is out of scope but the transport must not crash on disconnect).
• Unit tests cover SendAsync, SendBatchAsync, and IsHealthyAsync (healthy and unhealthy states).
• Integration tests use Testcontainers.RabbitMq to verify publishing behavior against a real broker.
• XML documentation is provided for all public members.

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Out of Scope

• Message consumption/subscription.
• Exchange or queue auto-declaration.
• Connection pooling or reconnection policies (recommended to combine with Polly).
• AMQP 1.0 support.