Bug Report: ee.on is not a function Error with @codegenie/serverless-express 4.16.0

### __Environment:__

- __@codegenie/serverless-express:__ 4.16.0 (error occurs) / 4.15.0 (works)
- __Express:__ 4.19.2
- __Node.js:__ 20.x (AWS Lambda runtime)
- __TypeScript:__ 5.7.3

### __Error Description:__

When using @codegenie/serverless-express version 4.16.0, the following error occurs consistently in AWS Lambda:

```javascript
TypeError: ee.on is not a function
at first (/var/task/node_modules/ee-first/index.js:43:10)
at onSocket (/var/task/node_modules/on-finished/index.js:115:16)
at attachFinishedListener (/var/task/node_modules/on-finished/index.js:120:5)
at attachListener (/var/task/node_modules/on-finished/index.js:147:5)
at onFinished (/var/task/node_modules/on-finished/index.js:53:3)
at send (/var/task/node_modules/finalhandler/index.js:314:3)
at /var/task/node_modules/finalhandler/index.js:133:5
at /var/task/node_modules/express/lib/router/index.js:646:15
at next (/var/task/node_modules/express/lib/router/index.js:265:14)
at urlencodedParser (/var/task/node_modules/body-parser/lib/types/urlencoded.js:91:7)
```

### __Root Cause:__

The error appears to be introduced in version 4.16.0 of @codegenie/serverless-express. The `ee-first` library expects an EventEmitter-like object but receives something that doesn't have the `.on()` method, suggesting a regression in how response objects are handled in the Lambda environment.

### __Reproduction Steps:__

1. Create a Lambda function with @codegenie/serverless-express 4.16.0
2. Set up basic Express routes
3. Deploy to AWS Lambda
4. Make any HTTP request to the Lambda function

### __Workaround/Solution:__

Downgrade to the previous working version:

```json
{
"@codegenie/serverless-express": "^4.15.0"
}
```

### __Code Pattern That Triggers Error:__

```typescript
import express from 'express';
import serverlessExpress from '@codegenie/serverless-express';

const app = express();
app.get('/health', (req, res) => res.send('ok'));

// This pattern causes the error with version 4.16.0
const serverlessHandler = serverlessExpress({ app });

export const handler = async (event, context) => {
return serverlessHandler(event, context, () => {});
};
```

### __Expected Behavior:__

The serverless handler should process requests without throwing `ee.on is not a function` errors.

### __Actual Behavior:__

The error occurs during response processing, specifically when Express tries to attach event listeners for response completion tracking.

### __Additional Context:__

- The error only occurs in AWS Lambda environment, not in local development
- The error happens after successful initialization but during request processing
- Downgrading to 4.15.0 completely resolves the issue
- This suggests a regression introduced in version 4.16.0

### __Version Comparison:__

- __4.15.0:__ ✅ Works correctly
- __4.16.0:__ ❌ Throws `ee.on is not a function` error

### __Suggested Investigation:__

Please review changes made between versions 4.15.0 and 4.16.0, particularly around response object handling and event emitter interactions in the Lambda environment.