Add "Custom Request" field to checkout form

[catherineisonline]

Add a new input field in the checkout form where users can type in custom requests (e.g., “Leave package at the door”, “Gift wrap”, etc.). This field should be optional.

Criteria:

A new text field labeled “Custom Request” is added to the checkout form.

The field should be optional, the user can submit the form if it is empty.

The submitted value should be stored and passed along with the order details.