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/alerting/README.md

@@ -0,0 +1,50 @@
+# alerting
+
+Alerting Module
+
+## Usage
+
+```hcl
+module "alerting" {
+  source = "../modules/alerting"
+  
+  # Required variables
+  name = ""
+
+  # Optional: see variables.tf for all options
+}
+```
+
+## Requirements
+
+| Name | Version |
+|------|---------|
+| terraform | >= 1.5.0 |
+| aws | >= 5.0 |
+
+## Inputs
+
+| Name | Description | Type | Required |
+|------|-------------|------|----------|
+| name | Name prefix for alerting resources | `string` | yes |
+| email_endpoints | Email addresses to receive alerts | `list(string)` | no |
+| email_endpoints_critical | Email addresses for critical alerts only (uses email_endpoin... | `list(string)` | no |
+| slack_webhook_url | Slack webhook URL for notifications | `string` | no |
+| pagerduty_endpoint | PagerDuty Events API endpoint | `string` | no |
+| enable_aws_health_events |  | `bool` | no |
+| enable_guardduty_events |  | `bool` | no |
+| enable_securityhub_events |  | `bool` | no |
+| tags |  | `map(string)` | no |
+
+## Outputs
+
+| Name | Description |
+|------|-------------|
+| critical_topic_arn | SNS topic for critical alerts |
+| warning_topic_arn | SNS topic for warning alerts |
+| info_topic_arn | SNS topic for info alerts |
+| topics |  |
+
+## License
+
+Apache 2.0 - See LICENSE for details.