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/pdf/InvoiceDocument.tsx

@@ -52,6 +52,11 @@ const styles = StyleSheet.create({
   recipientBlock: {
     width: "55%",
   },
+  recipientBlockFull: {
+    flexDirection: "row",
+    justifyContent: "space-between",
+    marginBottom: 20,
+  },
   recipientName: {
     fontFamily: "Helvetica-Bold",
     fontSize: 10,
@@ -69,7 +74,10 @@ const styles = StyleSheet.create({
     marginBottom: 2,
   },
   metaBlock: {
-    width: "40%",
+    width: "45%",
+  },
+  metaBlockHeader: {
+    width: "50%",
   },
   metaTable: {
     flexDirection: "column",
@@ -85,6 +93,11 @@ const styles = StyleSheet.create({
   metaValue: {
     fontFamily: "Helvetica-Bold",
   },
+  unitOriginalStrike: {
+    color: TEXT_MUTED,
+    textDecoration: "line-through",
+    fontSize: 7,
+  },
   invoiceNumberBig: {
     color: BRAND_BLUE,
     fontFamily: "Helvetica-Bold",
@@ -270,31 +283,14 @@ export function InvoiceDocument({ invoice }: DocProps) {
           </Text>
         )}
 
-        <Header issuer={invoice.issuer} />
-
         <View style={styles.headerRow}>
-          <View style={styles.recipientBlock}>
-            <Text style={styles.senderLine}>{senderInline(invoice.issuer)}</Text>
-            <Recipient recipient={invoice.recipient} />
-            {invoice.separateShippingAddress ? (
-              <View style={styles.shippingAddressBlock}>
-                <Text style={styles.shippingAddressHeading}>{t.shippingAddressHeading}</Text>
-                <Recipient recipient={invoice.separateShippingAddress} />
-              </View>
-            ) : null}
-          </View>
-          <View style={styles.metaBlock}>
+          {invoice.issuer.logoDataUrl ? (
+            <Image src={invoice.issuer.logoDataUrl} style={styles.logo} />
+          ) : (
+            <View />
+          )}
+          <View style={styles.metaBlockHeader}>
             <View style={styles.metaTable}>
-              <View style={styles.metaRow}>
-                <Text style={styles.metaLabel}>{invoice.kind === "offer" ? t.offerNumber : t.invoiceNumber}</Text>
-                <Text style={styles.invoiceNumberBig}>{invoice.number}</Text>
-              </View>
-              {invoice.kind === "invoice" && invoice.orderName ? (
-                <View style={styles.metaRow}>
-                  <Text style={styles.metaLabel}>{t.orderNumberLabel}</Text>
-                  <Text style={styles.metaValue}>{invoice.orderName}</Text>
-                </View>
-              ) : null}
               <View style={styles.metaRow}>
                 <Text style={styles.metaLabel}>{invoice.kind === "offer" ? t.offerDate : t.invoiceDate}</Text>
                 <Text style={styles.metaValue}>{formatDate(invoice.invoiceDate, invoice.language)}</Text>
@@ -327,6 +323,12 @@ export function InvoiceDocument({ invoice }: DocProps) {
                   </Text>
                 </View>
               )}
+              {invoice.kind === "invoice" && invoice.discountCodes.length > 0 ? (
+                <View style={styles.metaRow}>
+                  <Text style={styles.metaLabel}>{t.discountCodeLabel}</Text>
+                  <Text style={styles.metaValue}>{invoice.discountCodes.join(", ")}</Text>
+                </View>
+              ) : null}
               {invoice.kind === "invoice" && invoice.shippingMethod ? (
                 <View style={styles.metaRow}>
                   <Text style={styles.metaLabel}>{t.shippingMethodLabel}</Text>
@@ -350,6 +352,19 @@ export function InvoiceDocument({ invoice }: DocProps) {
           </View>
         </View>
 
+        <View style={styles.recipientBlockFull}>
+          <View style={styles.recipientBlock}>
+            <Text style={styles.senderLine}>{senderInline(invoice.issuer)}</Text>
+            <Recipient recipient={invoice.recipient} />
+          </View>
+          {invoice.separateShippingAddress ? (
+            <View style={styles.recipientBlock}>
+              <Text style={styles.shippingAddressHeading}>{t.shippingAddressHeading}</Text>
+              <Recipient recipient={invoice.separateShippingAddress} />
+            </View>
+          ) : null}
+        </View>
+
         <Text style={styles.title}>
           {invoice.kind === "storno"
             ? t.stornoInvoice
@@ -357,6 +372,9 @@ export function InvoiceDocument({ invoice }: DocProps) {
               ? t.offer
               : t.invoice}{" "}
           Nr. {invoice.number}
+          {invoice.kind === "invoice" && invoice.orderName
+            ? `   ·   ${t.orderNumberLabel}: ${invoice.orderName}`
+            : ""}
         </Text>
 
         <Text style={styles.paragraph}>{t.salutationGeneric}</Text>
@@ -474,14 +492,12 @@ function senderInline(issuer: IssuerData): string {
     .join(" - ");
 }
 
-function Header({ issuer }: { issuer: IssuerData }) {
-  return (
-    <View style={styles.headerRow}>
-      <View>{/* spacer; logo is right-aligned */}</View>
-      {issuer.logoDataUrl ? <Image src={issuer.logoDataUrl} style={styles.logo} /> : <View />}
-    </View>
-  );
+function Header(_args: { issuer: IssuerData }) {
+  // Deprecated: header rendering is now inlined in InvoiceDocument so the
+  // logo and meta block can share a single row at the top of the page.
+  return null;
 }
+void Header;
 
 function Recipient({ recipient }: { recipient: RecipientData }) {
   const lines: string[] = [];
@@ -529,7 +545,14 @@ function LineRow({
         </View>
       </View>
       <Text style={styles.colQty}>{formatQuantity(line.quantity, t.pieceUnit, language)}</Text>
-      <Text style={styles.colUnit}>{formatMoney(line.unitPriceNet, currency, language)}</Text>
+      <View style={styles.colUnit}>
+        {line.originalUnitPriceNet != null ? (
+          <Text style={styles.unitOriginalStrike}>
+            {formatMoney(line.originalUnitPriceNet, currency, language)}
+          </Text>
+        ) : null}
+        <Text>{formatMoney(line.unitPriceNet, currency, language)}</Text>
+      </View>
       <Text style={styles.colTotal}>{formatMoney(line.totalNet, currency, language)}</Text>
     </View>
   );