Update README to document OAuth2, SSEv2, PubSub patterns, and completed roadmap items

[Copilot]

The README was outdated, missing documentation for OAuth2 authentication, SSEv2 implementation, advanced PubSub patterns, and several completed roadmap items.

New Features Documented

Authentication & Services

• OAuth2 support with generic provider (Google, GitHub, Facebook, Microsoft)
• SSEv2 with broker architecture, event replay, and persistent event store
• PubSub enterprise patterns: CQRS, Saga, Event Sourcing, Outbox, Request-Reply, Priority Queue, Batch
• PubSub middleware stack (logging, recovery, timeout, metrics, circuit breaker)
• Swagger/OpenAPI documentation generation
• Database migration tool (cmd/migrate)

Architecture Updates

• Added core/auth/oauth/, core/docs/, services/ssev2/
• Detailed services/pubsub/ subdirectories: patterns/, middleware/, observability/, serializers/

Code Examples Added

OAuth2 Authentication

provider := oauth.GoogleProvider
authenticator := oauth.NewGenericAuthenticator(oauthConfig, provider)
user, _ := authenticator.GetUser(token)

CQRS Pattern

commandBus := patterns.NewCommandBus(broker)
commandBus.RegisterHandler(&CreateUserHandler{})
commandBus.Send(ctx, command)

Saga Pattern with Compensation

saga := patterns.NewSaga("order-123", publisher)
saga.AddStep(&patterns.SagaStep{
    Action: processPayment,
    Compensation: refundPayment,
})
saga.Execute(ctx, orderData)  // Auto-compensates on failure

SSEv2 with Event Replay

broker := ssev2.NewBroker(config)
events, _ := broker.GetEventsSince("topic", lastEventID)  // Replay missed events

Roadmap Updates

• Marked v0.1, v0.2, v0.3 as completed
• Renumbered subsequent versions to reflect actual progress
• Current state: 15+ major features completed, v0.4 in progress

Original prompt

Revisa el codigo y actualiza el readme para reflejar los cambios y avances del roadmap y cosas q se hayan agregado

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