Fixed delivery address prefill and validation

We've fixed an issue where switching from a flat-fee delivery option to a per-mile delivery option incorrectly prefilled the delivery address with the billing address. You can now rely on Google Address Validation to flag invalid or incorrect delivery addresses, which reduced misdeliveries and last-minute customer calls. We've also simplified delivery address checks by using Google’s validation instead of hardcoded distance limits, so valid addresses went through more consistently.