feat(Production): Complete production deployment infrastructure

- Add comprehensive health check system with multiple endpoints
- Add Prometheus metrics endpoint
- Add production logging configurations (5 strategies)
- Add complete deployment documentation suite:
  * QUICKSTART.md - 30-minute deployment guide
  * DEPLOYMENT_CHECKLIST.md - Printable verification checklist
  * DEPLOYMENT_WORKFLOW.md - Complete deployment lifecycle
  * PRODUCTION_DEPLOYMENT.md - Comprehensive technical reference
  * production-logging.md - Logging configuration guide
  * ANSIBLE_DEPLOYMENT.md - Infrastructure as Code automation
  * README.md - Navigation hub
  * DEPLOYMENT_SUMMARY.md - Executive summary
- Add deployment scripts and automation
- Add DEPLOYMENT_PLAN.md - Concrete plan for immediate deployment
- Update README with production-ready features

All production infrastructure is now complete and ready for deployment.

src/Framework/EventSourcing/Sagas/SagaInterface.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Framework\EventSourcing\Sagas;
+
+use App\Framework\EventSourcing\DomainEvent;
+
+/**
+ * Saga Interface
+ *
+ * Long-running business processes that coordinate across multiple aggregates
+ * Also known as Process Managers in DDD terminology
+ */
+interface SagaInterface
+{
+    /**
+     * Get unique saga identifier
+     */
+    public function getSagaId(): SagaId;
+
+    /**
+     * Get saga name for identification
+     */
+    public function getName(): string;
+
+    /**
+     * Handle incoming event
+     * Returns commands to be executed as result of event
+     *
+     * @return array<object> Commands to execute
+     */
+    public function handle(DomainEvent $event): array;
+
+    /**
+     * Get events this saga is interested in
+     *
+     * @return array<class-string> Event class names
+     */
+    public function subscribedTo(): array;
+
+    /**
+     * Get current saga state
+     */
+    public function getState(): SagaState;
+
+    /**
+     * Check if saga is completed
+     */
+    public function isCompleted(): bool;
+
+    /**
+     * Compensate (rollback) saga on failure
+     * Returns compensation commands
+     *
+     * @return array<object> Compensation commands
+     */
+    public function compensate(string $reason): array;
+}