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/backup-plan/README.md

@@ -0,0 +1,54 @@
+# backup-plan
+
+AWS Backup Module
+
+## Usage
+
+```hcl
+module "backup_plan" {
+  source = "../modules/backup-plan"
+  
+  # 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 | Backup plan name | `string` | yes |
+| tenant | Tenant name for resource selection | `string` | no |
+| backup_tag_key | Tag key to select resources for backup | `string` | no |
+| backup_tag_value | Tag value to select resources for backup | `string` | no |
+| daily_retention_days |  | `number` | no |
+| weekly_retention_days |  | `number` | no |
+| monthly_retention_days |  | `number` | no |
+| enable_continuous_backup | Enable continuous backup for point-in-time recovery (RDS, S3... | `bool` | no |
+| enable_cross_region_copy |  | `bool` | no |
+| dr_region | DR region for cross-region backup copy | `string` | no |
+| dr_retention_days |  | `number` | no |
+| kms_key_arn | KMS key ARN for backup encryption (uses AWS managed key if n... | `string` | no |
+
+## Outputs
+
+| Name | Description |
+|------|-------------|
+| vault_arn |  |
+| vault_name |  |
+| plan_id |  |
+| plan_arn |  |
+| role_arn |  |
+
+## License
+
+Apache 2.0 - See LICENSE for details.