Replace print() with logger in ProxyManager

## Summary

`components/bot_detector/proxy_manager/core.py:45` calls `print()` with a referral message on init. Per code guidelines, should use `logger.info()`.

```python
print(f"To get an API key, please use our referral code: {referral}")
```

## Proposed Change

Replace `print()` with `logger.info()`.