feat(invoice): add Shopify order #, shipping address/method/cost and tracking

- Query Order.shippingLine and Order.fulfillments.trackingInfo from Admin GraphQL.
- Surface orderName (#1004) so customers recognise their order alongside the sequential invoice number.
- Render shipping cost as a synthetic line item (folds into the VAT breakdown).
- Show shipping method (Versandart / Shipping method) and tracking numbers (clickable when URL present) in the meta block.
- Render a separate delivery-address block when the shipping address differs from billing.
- DE strings stay informal (Versandart / Sendungsnummer / Lieferadresse / Versand).

app/services/invoice/i18n.ts

@@ -58,6 +58,11 @@ export interface InvoiceStrings {
   paymentStatusUnpaid: string;
   paymentStatusPartial: string;
   paymentStatusRefunded: string;
+  orderNumberLabel: string;
+  shippingAddressHeading: string;
+  shippingMethodLabel: string;
+  trackingLabel: string;
+  shippingItemPrefix: string;
 }
 
 /** Status displayed for the order's payment, derived from Shopify's
@@ -153,6 +158,11 @@ const de: InvoiceStrings = {
   paymentStatusUnpaid: "Offen",
   paymentStatusPartial: "Teilweise bezahlt",
   paymentStatusRefunded: "Erstattet",
+  orderNumberLabel: "Bestellnummer",
+  shippingAddressHeading: "Lieferadresse",
+  shippingMethodLabel: "Versandart",
+  trackingLabel: "Sendungsnummer",
+  shippingItemPrefix: "Versand",
 };
 
 const en: InvoiceStrings = {
@@ -215,6 +225,11 @@ const en: InvoiceStrings = {
   paymentStatusUnpaid: "Outstanding",
   paymentStatusPartial: "Partially paid",
   paymentStatusRefunded: "Refunded",
+  orderNumberLabel: "Order no.",
+  shippingAddressHeading: "Shipping address",
+  shippingMethodLabel: "Shipping method",
+  trackingLabel: "Tracking no.",
+  shippingItemPrefix: "Shipping",
 };
 
 // Locale → invoice language. We only render in German (`de`) when the