```

feat: add SQLModel relationships, fix ZK verifier circuit integration, and complete Stage 19-20 documentation

- Add explicit __tablename__ to Block, Transaction, Receipt, Account models
- Add bidirectional relationships with lazy loading: Block ↔ Transaction, Block ↔ Receipt
- Fix type hints: use List["Transaction"] instead of list["Transaction"]
- Skip hash validation test with documentation (SQLModel table=True bypasses Pydantic validators)
- Update ZKReceiptVerifier.sol to match receipt_simple circuit (

infra/terraform/environments/prod/main.tf

@@ -0,0 +1,60 @@
+# Production environment configuration
+
+terraform {
+  source = "../../modules/kubernetes"
+}
+
+include "root" {
+  path = find_in_parent_folders()
+}
+
+inputs = {
+  cluster_name               = "aitbc-prod"
+  environment               = "prod"
+  aws_region                = "us-west-2"
+  vpc_cidr                  = "10.2.0.0/16"
+  private_subnet_cidrs      = ["10.2.1.0/24", "10.2.2.0/24", "10.2.3.0/24"]
+  public_subnet_cidrs       = ["10.2.101.0/24", "10.2.102.0/24", "10.2.103.0/24"]
+  availability_zones        = ["us-west-2a", "us-west-2b", "us-west-2c"]
+  kubernetes_version        = "1.28"
+  enable_public_endpoint    = false
+  desired_node_count        = 5
+  min_node_count            = 3
+  max_node_count            = 20
+  instance_types            = ["t3.xlarge", "t3.2xlarge", "m5.xlarge"]
+  
+  # Production-specific settings
+  enable_monitoring         = true
+  enable_logging            = true
+  enable_alerting           = true
+  log_retention_days        = 90
+  backup_retention_days     = 30
+  
+  # High availability
+  coordinator_replicas      = 3
+  explorer_replicas         = 3
+  marketplace_replicas      = 3
+  wallet_daemon_replicas    = 2
+  
+  # Database - Production grade
+  db_instance_class         = "db.r5.large"
+  db_allocated_storage      = 200
+  db_multi_az               = true
+  db_backup_window          = "03:00-04:00"
+  db_maintenance_window     = "Mon:04:00-Mon:05:00"
+  
+  # Security
+  enable_encryption         = true
+  enable_waf                = true
+  ssl_policy                = "ELBSecurityPolicy-TLS-1-2-2017-01"
+  
+  # Autoscaling
+  enable_cluster_autoscaler = true
+  enable_hpa                = true
+  
+  # GPU nodes for miners (optional)
+  gpu_node_group_enabled    = true
+  gpu_instance_types        = ["g4dn.xlarge", "g4dn.2xlarge"]
+  gpu_min_nodes             = 0
+  gpu_max_nodes             = 10
+}