Add Terraform AWS infrastructure and enhanced CI/CD pipeline (FRE-4574)

- Terraform modules: VPC, ECS Fargate, RDS PostgreSQL, ElastiCache Redis, S3, Secrets Manager, CloudWatch
- Multi-environment support: staging and production configs
- ECS auto-scaling: CPU-based scaling with configurable min/max
- CI/CD: pnpm caching, Docker Buildx, Trivy security scanning, Terraform plan on PR
- Deploy: ECS service updates with automatic rollback on health check failure
- Backup: automated RDS snapshots, S3 versioning, ElastiCache snapshots
- Monitoring: CloudWatch dashboards, CPU/memory/5xx alarms
- Rollback script for manual service rollback
- Infrastructure documentation with architecture overview

infra/outputs.tf

@@ -0,0 +1,35 @@
+output "vpc_id" {
+  description = "VPC ID"
+  value       = module.vpc.vpc_id
+}
+
+output "cluster_name" {
+  description = "ECS cluster name"
+  value       = "${var.project_name}-${var.environment}"
+}
+
+output "rds_endpoint" {
+  description = "RDS endpoint"
+  value       = module.rds.db_endpoint
+  sensitive   = true
+}
+
+output "elasticache_endpoint" {
+  description = "ElastiCache primary endpoint"
+  value       = module.elasticache.cache_endpoint
+}
+
+output "s3_bucket_name" {
+  description = "S3 bucket name"
+  value       = module.s3.bucket_name
+}
+
+output "secrets_manager_arn" {
+  description = "Secrets Manager ARN"
+  value       = module.secrets.secrets_manager_arn
+}
+
+output "cloudwatch_dashboard_url" {
+  description = "CloudWatch dashboard URL"
+  value       = module.cloudwatch.dashboard_url
+}