Serverless deploy to LocalStack fails: “Invalid character in header content [authorization]”

Running serverless deploy --stage local against LocalStack aborts during the “Resolving AWS account ID” step with the error:
```bash
Unable to find function cleanup on plugin Esbuild
Deploying "sls" to stage "local" (us-east-1)
Using serverless-localstack
Using serverless-localstack
serverless-localstack: Reconfigured endpoints

Error: Failed to resolve AWS account ID: Invalid character in header content ["authorization"]
```
deployment never reaches packaging or CloudFormation synthesis

serverless.ts
```typescript
plugins: ['serverless-iam-roles-per-function', 'serverless-localstack'],

custom:
localstack:
stages: ['local']
edgePort: 4566
host: 'http://localhost'

provider:
name: aws
runtime: nodejs22.x
environment:
AWS_ENDPOINT_URL: 'http://localhost:4566'
AWS_ACCESS_KEY_ID: '000000000001'
AWS_ACCOUNT_ID: '000000000001'
```

docker-compose.yml
```yml
s3mock:
image: adobe/s3mock:latest
environment:
- retainFilesOnExit=true
- root=root
ports:
- 9090:9090
volumes:
- ./uploadedFiles:/root

localstack:
container_name: localstack
image: localstack/localstack
ports:
- 4566:4566
- 4510-4559:4510-4559
environment:
- DEBUG=${DEBUG:-0}
- SERVICES=lambda,sqs,sns
volumes:
- '${LOCALSTACK_VOLUME_DIR:-./volume}:/var/lib/localstack'
- '/var/run/docker.sock:/var/run/docker.sock'
```

**Versions**
| Component | Version |
|--------------------------|-------------------------------------------------------|
| Serverless Framework | 4.14.3 |
| serverless-localstack | 1.3.1 |
| LocalStack Docker image | `localstack/localstack:latest` (pulled 2025-05-14) |
| Node.js | 22.0.0 |

Reproduce `serverless deploy --stage local` using `serverless.ts` and `docker-compose.yml`, focusing on the “Resolving AWS account ID” step and the authorization-header error. Check the listed Serverless Framework, serverless-localstack, LocalStack, and Node.js versions. Done means deployment proceeds beyond account resolution to packaging and CloudFormation synthesis without the invalid-header failure.

Written by the indexing model from the issue text.