[gen2-migration] Adopted S3 bucket: policy/notification sub-resources reference a different bucket than the adopted bucket

## Summary
For an adopted S3 bucket, the generated bucket resource is repointed to the existing bucket, but its bucket-policy and notification sub-resources are still generated against a different (CDK-synthesized) bucket reference — an internal inconsistency within the storage construct.

## Expected
All sub-resources (policy, notifications) for an adopted bucket should consistently reference the adopted bucket.

## Note
May present as an intermediate state prior to post-refactor reconciliation; filing so it isn't dismissed as expected transient state.

## Type
Bug

Start by tracing the storage construct that generates an adopted S3 bucket and its bucket-policy and notification sub-resources. Compare the bucket references used by the generated resources; done means the policy and notifications consistently reference the adopted bucket rather than a different synthesized bucket.

Written by the indexing model from the issue text.