Add ack-resource-adoption-from-iac custom transformation

[brunokktro]

Summary

Adds a new community-sourced custom transformation for AWS Transform: ACK Resource Adoption from IaC.

Analyzes CloudFormation, Terraform, and Pulumi code and generates ACK (AWS Controllers for Kubernetes) adoption manifests that bring existing AWS resources under Kubernetes/GitOps management without recreating, modifying, or deleting anything - using the ResourceAdoption feature gate with adopt-or-create policy and deletion-policy: retain on every manifest. IaC modules and CloudFormation nested stacks are translated into kro ResourceGraphDefinitions, preserving reusable composition as Kubernetes-native APIs.

What's included

community-sourced-transformations/ack-resource-adoption-from-iac/
├── README.md            # Overview, getting started, troubleshooting, repository structure
├── SKILL.md             # Transformation definition: objective, scope, workflow, exit criteria
├── BENCHMARKS.md        # End-to-end test results (atx custom def exec against a real test repo)
└── references/
    ├── iac-to-ack-mapping.md      # CFN/Terraform/Pulumi -> ACK Kind mapping (26 resource types)
    ├── adoption-fields-ref.md     # Per-Kind adoption-fields reference with discovery commands
    ├── kro-patterns.md            # Module/nested stack -> ResourceGraphDefinition translation rules
    └── examples-iac-to-ack.md     # 6 worked before/after examples

Testing

Validated end-to-end via atx custom def exec against a mixed Terraform test repository (flat resources + reusable module + unsupported type). Results in BENCHMARKS.md:

• 5/5 generated ACK manifests carry adopt-or-create + deletion-policy: retain (programmatic annotation audit, including templates inside the RGD)
• Terraform module correctly translated to a kro RGD + instance CR, with module inputs as schema fields and internal references as CEL expressions
• aws_iam_role_policy_attachment correctly folded into the Role spec
• Unsupported resource (CloudWatch Log Group) flagged in ADOPTION_REPORT.md with guidance, never guessed
• Source IaC byte-identical after the run; zero IaC syntax remnants in outputs

Notes for reviewers

This submission already follows the review guidance from PR #72 (eks-version-upgrade-readiness): no internal links, BENCHMARKS.md with real execution results, a Troubleshooting section, and a Repository Structure tree in the README.