Resend Python SDK on AWS Lambda: package the SDK and map ResendError to a 500

# Python Lambda: bundle resend, env key, exception to status code

```python
import os
import resend
from resend.exceptions import ResendError

resend.api_key = os.environ["RESEND_API_KEY"]

def handler(event, context):
    params = {
        "from": "[SENDER]",
        "to": ["[RECIPIENT]"],
        "subject": "hello world",
        "html": "<strong>it works!</strong>",
    }
    try:
        email = resend.Emails.send(params)
        return {"statusCode": 200, "body": str(email)}
    except ResendError as error:
        print(error)
        return {"statusCode": 502, "body": "email provider error"}
```

## Checklist

- `resend` is not in the Lambda Python runtime. Install it into the deployment
  package (pip install into the bundle directory) or the import fails at cold
  start.
- Set `resend.api_key` at module scope from `os.environ` so warm invocations
  reuse it. Never hardcode the key in the handler file.
- Catch ResendError and return a status code. An uncaught exception is a 502
  with no useful signal; mapping it yourself keeps the failure legible.
- Do not return the raw exception to the caller. Log it, return a short error.