feat(invoice): per-line + cart discounts, fulfillment delivery date, pickup label, header layout refresh

- discounts: read discountedUnitPriceSet (per-line) and discountCode/discountCodes
  (order-level) from Shopify; render discounted unit price with strikethrough
  original on the invoice line and add a 'Rabattcode'/'Discount code' meta row
  when codes were used.
- delivery date: pick the latest fulfillment.createdAt for §11 UStG instead of
  hard-coding processedAt; fall back to invoice date when unfulfilled.
- pickup: detect Shopify Local Pickup (and 'Abholung'/'Pickup' custom rates) via
  shippingLine.source/code/title; suppress the pickup-location 'shipping address'
  block and render localized 'Abholung'/'Pick-up' as the shipping method.
- layout: move the company logo to the top-left and the meta block to the
  top-right, putting recipient (and any separate delivery address) on its own
  row below; drop the standalone invoice-/order-number meta rows and surface
  them inside the title (e.g. 'Rechnung Nr. RE-1004 · Bestellnummer: #1004') to
  recover vertical space.
- tests: smoke fixtures cover discount, pickup, and fulfillment-date variants
  without disturbing the AT B2B totals.

app/services/invoice/loadOrderForInvoice.server.ts

@@ -25,6 +25,10 @@ export interface RawOrderForInvoice {
   taxLines: RawTaxLine[];
   shippingLine: RawShippingLine | null;
   fulfillments: RawFulfillment[];
+  /** Discount codes applied to the cart (e.g. `["SUMMER10"]`). Empty when
+   *  no codes were used. Manual / automatic discounts without a code are
+   *  not exposed here. */
+  discountCodes: string[];
   taxesIncluded: boolean;
   subtotalSet: { shopMoney: RawMoney } | null;
   totalTaxSet: { shopMoney: RawMoney } | null;
@@ -59,6 +63,10 @@ export interface RawLineItem {
   sku: string | null;
   quantity: number;
   originalUnitPriceSet: { shopMoney: RawMoney };
+  /** Per-unit price after Shopify has allocated cart-level discounts to this
+   *  line. May be null when no discount applied (in which case use the
+   *  original price). */
+  discountedUnitPriceSet: { shopMoney: RawMoney } | null;
   taxLines: RawTaxLine[];
   imageUrl: string | null;
 }
@@ -87,6 +95,10 @@ export interface RawTrackingInfo {
 }
 
 export interface RawFulfillment {
+  /** ISO timestamp of when the fulfillment was created (i.e. when the goods
+   *  were dispatched / handed over). Used for the legally-required delivery
+   *  date on the invoice when present. */
+  createdAt: string | null;
   trackingInfo: RawTrackingInfo[];
 }
 
@@ -137,6 +149,8 @@ const QUERY = `#graphql
         ratePercentage
         priceSet { shopMoney { amount currencyCode } }
       }
+      discountCode
+      discountCodes
       shippingLine {
         title
         code
@@ -152,6 +166,7 @@ const QUERY = `#graphql
         }
       }
       fulfillments(first: 10) {
+        createdAt
         trackingInfo {
           number
           url
@@ -165,6 +180,7 @@ const QUERY = `#graphql
             sku
             quantity
             originalUnitPriceSet { shopMoney { amount currencyCode } }
+            discountedUnitPriceSet { shopMoney { amount currencyCode } }
             image { url altText }
             taxLines {
               title
@@ -220,6 +236,8 @@ interface RawAdminResponse {
       totalTaxSet: { shopMoney: RawMoney } | null;
       totalPriceSet: { shopMoney: RawMoney } | null;
       taxLines: RawTaxLine[];
+      discountCode: string | null;
+      discountCodes: string[] | null;
       shippingLine: RawShippingLine | null;
       fulfillments: RawFulfillment[] | null;
       lineItems: { edges: { node: RawLineItem }[] };
@@ -270,6 +288,9 @@ export async function loadOrderForInvoice(
     totalTaxSet: order.totalTaxSet,
     totalPriceSet: order.totalPriceSet,
     taxLines: order.taxLines || [],
+    discountCodes: order.discountCodes && order.discountCodes.length > 0
+      ? order.discountCodes
+      : (order.discountCode ? [order.discountCode] : []),
     shippingLine: order.shippingLine ?? null,
     fulfillments: order.fulfillments ?? [],
     lineItems: (order.lineItems?.edges || []).map((e) => {
@@ -279,6 +300,7 @@ export async function loadOrderForInvoice(
         sku: node.sku,
         quantity: node.quantity,
         originalUnitPriceSet: node.originalUnitPriceSet,
+        discountedUnitPriceSet: node.discountedUnitPriceSet ?? null,
         taxLines: node.taxLines,
         imageUrl: node.image?.url ?? null,
       };