Fix phone validation

[karrisanthoshigayatri]

Fix: Checkout form phone number validation issue
📌 Problem

The checkout form was allowing users to proceed even with empty or invalid phone numbers. This could lead to incorrect order details and failed communication.

✅ Changes Made
Added validation for phone number field
Ensured field is required before form submission
Restricted input to valid numeric format
Prevented form submission if validation fails
Added user-friendly error feedback for invalid input
🎯 Result

Checkout form now properly validates phone numbers, improving data accuracy and order reliability.

[vercel]

@karrisanthoshigayatri is attempting to deploy a commit to the adithyansubramani1-1657's projects Team on Vercel.

A member of the Team first needs to authorize it.

[karrisanthoshigayatri]

The phone number validation issue has been fixed and tested successfully.

The Vercel check is awaiting authorization because I do not have permission to deploy to the repository owner's Vercel team. This is unrelated to the code changes.

The implementation is complete and ready for review.