feat(rechnung): branded invoice with VAT ID and per-rate grouping

The invoice PDF and the invoice page now share one branded layout:
logo (uploaded brand logo, otherwise the drawn honeycomb mark) and
wordmark in the header, honey accents, a forest-green table header,
a meta box with invoice number, date, order number and VAT ID, and a
footer with address, contact, VAT ID and page numbers on every page.

A mixed cart (e.g. honey at 7 % and a beeswax candle at 19 %) lists
its items in one block per VAT rate with a subtotal each. Next to the
totals, a VAT table shows net, VAT and gross per rate plus a sum row.
Long invoices continue on further pages with the table header repeated.

The VAT identification number is a new company field
(company.vatId), editable in Admin > Inhalte, defaulting to the
number already stated in the imprint.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

src/i18n/dictionaries/en.ts

@@ -1561,21 +1561,33 @@ export const en: Dictionary = {
     loginRequiredError: "Please sign in to view the invoice.",
     backToOrders: "Back to my orders",
     downloadPdf: "Download PDF",
-    invoiceLabel: (invoiceNumber) => `Invoice ${invoiceNumber}`,
-    orderLabel: (orderNumber) => `Order ${orderNumber}`,
-    dateLabel: "Date:",
+    documentTitle: "Invoice",
+    billedToLabel: "Billed to",
+    invoiceNumberLabel: "Invoice number",
+    invoiceDateLabel: "Invoice date",
+    orderNumberLabel: "Order number",
+    vatIdLabel: "VAT ID",
     itemHeader: "Item",
+    vatRateHeader: "VAT",
     quantityHeader: "Qty",
-    priceHeader: "Price",
+    priceHeader: "Unit price",
     totalHeader: "Total",
+    groupHeading: (ratePercent) => `Items at ${ratePercent}% VAT`,
+    groupSubtotalLabel: (ratePercent) => `Subtotal ${ratePercent}%`,
     subtotalLabel: "Subtotal",
     shippingLabel: "Shipping",
     freeShipping: "free",
     discountLabel: "Discount",
-    netLabel: "Net amount",
-    vatLabel: (ratePercent) => `plus ${ratePercent}% VAT`,
+    taxSummaryHeading: "VAT included",
+    taxRateHeader: "Rate",
+    netHeader: "Net",
+    vatAmountHeader: "VAT",
+    grossHeader: "Gross",
     smallBusinessNote: "No VAT is charged (small-business scheme, § 19 German VAT Act).",
-    totalLabel: "Total",
+    totalLabel: "Total amount",
+    pricesIncludeVat: "All prices include statutory VAT.",
+    thankYou: "Thank you for supporting our apiary!",
+    pageLabel: (page, total) => `Page ${page} of ${total}`,
     legalNote: "This invoice was generated automatically and is valid without a signature.",
   },
   addressesPage: {