Stale domain association for deleted app blocks new app - allisterevents.okaywinston.com

## Issue

A domain association for a **deleted** Amplify app is blocking a new app from claiming the same subdomain.

**Account:** 026090538781
**Region:** us-east-1
**Subdomain:** `allisterevents.okaywinston.com`
**New App ID:** `d24nyugd8w0wp3`

## Steps to reproduce

1. Had an Amplify app with domain association for `allisterevents.okaywinston.com`
2. Deleted the app
3. Created new app `d24nyugd8w0wp3`
4. Tried `aws amplify create-domain-association --app-id d24nyugd8w0wp3 --domain-name okaywinston.com --sub-domain-settings '[{"prefix":"allisterevents","branchName":"main"}]'`

## Error

```
BadRequestException: One or more domains requested are already associated with another Amplify app: allisterevents.okaywinston.com
```

Also blocked at CloudFront level: `CNAMEAlreadyExists` when attempting to create a CloudFront distribution with this CNAME alias, even though the old CloudFront distribution (`d2fb89kwqcfdsw.cloudfront.net`) is no longer in our account.

## Expected behavior

Deleting an Amplify app should release its domain associations so they can be used with new apps.

## Workaround

Using `events.okaywinston.com` as a different subdomain for now.

Start by reproducing the reported AWS Amplify create-domain-association command in us-east-1 with app d24nyugd8w0wp3 and the allisterevents prefix. Check whether the deleted association and CloudFront alias still block the request; done means the new app can claim allisterevents.okaywinston.com without the reported errors.

Written by the indexing model from the issue text.