I need my current Shopify checkout updated so customers can enter a few extra details in the shipping section and still move smoothly through payment. At minimum I want additional fields for shipping—think delivery instructions or a contact phone—captured in the order record and shown in the admin. The existing billing address flow can stay as Shopify presents it, but keep the structure flexible in case we later decide to add a quick “copy from shipping” toggle. Please make the change with an approach fully compatible with Shopify’s checkout requirements (Checkout UI extensions, checkout.liquid on Plus, or another native-friendly method you recommend). Once done, test across desktop and mobile, confirm the new data feeds through to the order timeline, and leave me a short note outlining the exact files or extensions touched so I can maintain them going forward.