LocalStack archives repo, requires auth token

This is a classic open-core boundary move: LocalStack is not killing the product, but it is ending the old "pull latest and go" workflow that made the community repo feel frictionless. The archive notice is symbolic; the real change is that the newest image now sits behind account-based access.

• –The repo itself says it is archived and read-only, with development consolidated into a unified image: [GitHub repo](https://github.com/localstack/localstack)
• –LocalStack's migration post says the single image will require a user account and auth token from March 23, 2026: [migration post](https://blog.localstack.cloud/localstack-single-image-next-steps/)
• –CI is the sharpest breakage point: any pipeline pulling `localstack/localstack:latest` needs an auth token or a pin before the cutoff.
• –The free non-commercial tier softens the blow for hobbyists, but the new flow still adds friction for anyone who expected fully anonymous pulls.