Fix email module import conflict

- Renamed vidai/email.py to vidai/email_utils.py to avoid conflict with built-in email module
- Updated import in payments.py
- This resolves the server startup issue caused by module shadowing

vidai/payments.py

@@ -24,7 +24,7 @@ import json
 from typing import Dict, Any, Optional, Tuple, List
 from .config import get_config
 from .database import update_user_tokens
-from .email import send_payment_confirmation
+from .email_utils import send_payment_confirmation
 
 
 class PaymentProcessor: