feat: Terraform Foundation - AWS Landing Zone

Enterprise-grade multi-tenant AWS cloud foundation.

Modules:
- GitHub OIDC for keyless CI/CD authentication
- IAM account settings and security baseline
- AWS Config Rules for compliance
- ABAC (Attribute-Based Access Control)
- SCPs (Service Control Policies)

Features:
- Multi-account architecture
- Cost optimization patterns
- Security best practices
- Comprehensive documentation

Tech: Terraform, AWS Organizations, IAM Identity Center

terraform/modules/budget-alerts/README.md

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+# budget-alerts
+
+Budget Alerts Module
+
+## Usage
+
+```hcl
+module "budget_alerts" {
+  source = "../modules/budget-alerts"
+  
+  # Required variables
+  monthly_budget = ""
+
+  # Optional: see variables.tf for all options
+}
+```
+
+## Requirements
+
+| Name | Version |
+|------|---------|
+| terraform | >= 1.5.0 |
+| aws | >= 5.0 |
+
+## Inputs
+
+| Name | Description | Type | Required |
+|------|-------------|------|----------|
+| name_prefix | Prefix for budget names | `string` | no |
+| monthly_budget | Monthly budget amount in USD | `number` | yes |
+| currency | Budget currency | `string` | no |
+| alert_emails | Email addresses for budget alerts | `list(string)` | no |
+| alert_sns_topic_arn | SNS topic ARN for alerts (creates one if empty) | `string` | no |
+| alert_thresholds | Alert thresholds as percentage of budget | `list(number)` | no |
+| forecast_alert_threshold | Alert when forecasted spend exceeds this percentage | `number` | no |
+| service_budgets |  | `map(number)` | no |
+| enable_anomaly_detection | Enable AWS Cost Anomaly Detection | `bool` | no |
+| anomaly_threshold_percentage | Anomaly alert threshold as percentage above expected | `number` | no |
+| anomaly_threshold_absolute | Minimum absolute dollar amount for anomaly alerts | `number` | no |
+| tags |  | `map(string)` | no |
+
+## Outputs
+
+| Name | Description |
+|------|-------------|
+| monthly_budget_id | Monthly budget ID |
+| service_budget_ids |  |
+| sns_topic_arn | SNS topic ARN for alerts |
+| anomaly_monitor_arn | Cost Anomaly Monitor ARN |
+| budget_summary |  |
+
+## License
+
+Apache 2.0 - See LICENSE for details.