Fixed: addresses without a postal code now save on a subscription

If a subscriber lives in a country that has no postal codes, you can now edit their subscription's delivery address in Subi and press Save. Before, the form demanded a postal code that doesn't exist there, so the save was refused every time.

This affects the 67 countries where Shopify's own address form has no postal code field, including Hong Kong, the United Arab Emirates and Qatar. For those countries the field on the delivery address window now reads "Postal code (optional)", and an empty value saves.

Everywhere else, a postal code is still required, and an empty one is still refused, as before.

The delivery address window also gets a country-code menu on the Phone field.

The customer portal's address form is unchanged and still asks for a postal code, although the portal's backend now also accepts an address without one in those countries.