refactor(invoice): drop dead paid/paidStamp; classify VOIDED; warn on unknown payment status

Audit cleanup of payment-status code paths uncovered while shipping
the partial-refund fix:

#1 Drop `viewModel.paid` (boolean). It was set from
   `displayFinancialStatus === "PAID"` and never read anywhere. With
   refunds in the picture it had become a footgun: a fully refunded
   order that started PAID would still satisfy `paid === true`, but
   `paymentStatus === "refunded"`. Callers should use `paymentStatus`
   / `requiresPayment` exclusively.

#2 Remove the unused `paidStamp` translation ("BEZAHLT" / "PAID").
   Defined in both locales but never rendered.

#3 Classify VOIDED orders as a distinct `"voided"` payment status
   (rendered "Annulliert" / "Voided") instead of "unpaid". A voided
   order had its authorisation cancelled before capture — no money
   was received and none is owed. The previous "Offen" / "Outstanding"
   label combined with a GiroCode would have invited the customer to
   pay an order that's already been called off. `requiresPayment`
   now also excludes `"voided"`, so GiroCode + payment-terms
   paragraph are suppressed (mirrors the `"refunded"` treatment).
   "Annulliert" is used in German rather than "Storniert" to avoid
   confusion with our storno cancellation document concept.

#6 `derivePaymentStatus` now logs a `console.warn` when it
   encounters a non-empty `displayFinancialStatus` value that isn't
   one of the documented Shopify enum members (PAID, PARTIALLY_PAID,
   REFUNDED, PARTIALLY_REFUNDED, VOIDED, PENDING, AUTHORIZED,
   EXPIRED). Future Shopify enum additions will surface in logs
   instead of silently mapping to "unpaid".

EXPIRED stays mapped to "unpaid" — abandoned-checkout-style edge
case left intentionally for a separate decision (#4 in the audit).

Verification: render-sample now also exercises a VOIDED fixture
(status row "Annulliert", no GiroCode, no payment terms). tsc /
smoke / tests / build all green.

app/services/invoice/i18n.ts

@@ -66,13 +66,13 @@ export interface InvoiceStrings {
   emailLabel: string;
   webLabel: string;
   phoneLabel: string;
-  paidStamp: string;
   paymentMethodLabel: string;
   paymentStatusLabel: string;
   paymentStatusPaid: string;
   paymentStatusUnpaid: string;
   paymentStatusPartial: string;
   paymentStatusRefunded: string;
+  paymentStatusVoided: string;
   orderNumberLabel: string;
   shippingAddressHeading: string;
   shippingMethodLabel: string;
@@ -97,7 +97,12 @@ export interface InvoiceStrings {
 
 /** Status displayed for the order's payment, derived from Shopify's
  *  `displayFinancialStatus`. */
-export type PaymentStatus = "paid" | "unpaid" | "partial" | "refunded";
+export type PaymentStatus =
+  | "paid"
+  | "unpaid"
+  | "partial"
+  | "refunded"
+  | "voided";
 
 export function paymentStatusLabel(
   status: PaymentStatus,
@@ -110,13 +115,27 @@ export function paymentStatusLabel(
       return strings.paymentStatusPartial;
     case "refunded":
       return strings.paymentStatusRefunded;
+    case "voided":
+      return strings.paymentStatusVoided;
     default:
       return strings.paymentStatusUnpaid;
   }
 }
 
-/** Maps Shopify's `displayFinancialStatus` to our condensed enum. Values not
- *  signalling actual receipt of money map to "unpaid". */
+/** Maps Shopify's `displayFinancialStatus` to our condensed enum.
+ *
+ *  - PAID                                  → paid
+ *  - PARTIALLY_PAID                        → partial
+ *  - REFUNDED / PARTIALLY_REFUNDED         → refunded
+ *    (composeInvoice further reclassifies PARTIALLY_REFUNDED with a
+ *    refund < gross back to "paid".)
+ *  - VOIDED                                → voided
+ *    (authorisation cancelled before capture; no money was ever
+ *    received and none is owed — distinct from "unpaid".)
+ *  - PENDING / AUTHORIZED / EXPIRED / unknown → unpaid
+ *
+ *  Unknown values log a warning so we notice when Shopify adds a new
+ *  enum member. */
 export function derivePaymentStatus(
   displayFinancialStatus: string | null | undefined,
 ): PaymentStatus {
@@ -124,6 +143,14 @@ export function derivePaymentStatus(
   if (v === "PAID") return "paid";
   if (v === "PARTIALLY_PAID") return "partial";
   if (v === "REFUNDED" || v === "PARTIALLY_REFUNDED") return "refunded";
+  if (v === "VOIDED") return "voided";
+  if (v && v !== "PENDING" && v !== "AUTHORIZED" && v !== "EXPIRED") {
+    console.warn(
+      `[invoice] derivePaymentStatus: unknown displayFinancialStatus ${JSON.stringify(
+        displayFinancialStatus,
+      )} — falling back to "unpaid".`,
+    );
+  }
   return "unpaid";
 }
 
@@ -184,13 +211,13 @@ const de: InvoiceStrings = {
   emailLabel: "E-Mail",
   webLabel: "Web",
   phoneLabel: "Tel.",
-  paidStamp: "BEZAHLT",
   paymentMethodLabel: "Zahlart",
   paymentStatusLabel: "Zahlstatus",
   paymentStatusPaid: "Bezahlt",
   paymentStatusUnpaid: "Offen",
   paymentStatusPartial: "Teilweise bezahlt",
   paymentStatusRefunded: "Erstattet",
+  paymentStatusVoided: "Annulliert",
   orderNumberLabel: "Bestellnummer",
   shippingAddressHeading: "Lieferadresse",
   shippingMethodLabel: "Versandart",
@@ -274,13 +301,13 @@ const en: InvoiceStrings = {
   emailLabel: "E-mail",
   webLabel: "Web",
   phoneLabel: "Tel.",
-  paidStamp: "PAID",
   paymentMethodLabel: "Payment method",
   paymentStatusLabel: "Payment status",
   paymentStatusPaid: "Paid",
   paymentStatusUnpaid: "Outstanding",
   paymentStatusPartial: "Partially paid",
   paymentStatusRefunded: "Refunded",
+  paymentStatusVoided: "Voided",
   orderNumberLabel: "Order no.",
   shippingAddressHeading: "Shipping address",
   shippingMethodLabel: "Shipping method",