fix(invoice): suppress GiroCode + payment terms for refunded (and paid) orders

User reported that fully refunded orders still rendered a SEPA GiroCode
QR asking the customer to wire the original total. The existing gate
("!viewModel.paid") only excluded literally-PAID orders; REFUNDED,
PARTIALLY_REFUNDED, VOIDED, AUTHORIZED, etc. all sneaked through and
produced a confusing payment request for an order whose outstanding
balance is in fact 0.

Root cause: the view model exposed two related but ambiguous flags
("paid" and "paymentStatus") and the renderer mixed them
inconsistently. Both the GiroCode generation step in
generateInvoice.server.tsx AND the GiroCode/payment-terms render gates
in InvoiceDocument.tsx checked the wrong one.

Fix: introduce a single derived "requiresPayment" flag on the view
model (composeInvoice.ts) that is true only when:
  - the document is a regular invoice (not a storno or an offer), AND
  - paymentStatus is neither "paid" nor "refunded".

That single flag now drives:
  - GiroCode QR generation (skip QR fetch for paid/refunded)
  - GiroCode block render in the PDF
  - payment-terms paragraph render in the PDF

The existing "Zahlstatus: Erstattet" / "Payment status: Refunded"
meta-row continues to communicate the refund visually — the change
just removes the contradictory call-to-pay.

Side benefits:
  - Storno (cancellation invoice) PDFs no longer emit the German
    "Bitte überweise …" payment-terms paragraph (kind=storno was
    falling through the same not-paid branch).
  - Same suppression for fully PAID orders (covered by a second smoke
    fixture) so the QR doesn't suggest re-payment after the fact.

Verification: new smoke fixtures (REFUNDED + PAID) build a real
GiroCode data URL and verify the PDF text neither contains the
"GiroCode" caption nor the "Bitte überweise" German payment terms,
while still showing the corresponding "Erstattet" / "Bezahlt" status
row. tsc / smoke / tests / build all green.

app/services/invoice/composeInvoice.ts

@@ -88,6 +88,12 @@ export function composeInvoice({
 
   const paid = (order.displayFinancialStatus || "").toUpperCase() === "PAID";
   const paymentStatus = derivePaymentStatus(order.displayFinancialStatus);
+  // A document only requires payment when it's a regular invoice (not a
+  // storno or an offer) AND money is still actually owed. Refunded and
+  // paid orders both have a 0 outstanding balance — the difference is
+  // just whether the money was kept (`paid`) or returned (`refunded`).
+  const requiresPayment =
+    !storno && !offer && paymentStatus !== "paid" && paymentStatus !== "refunded";
   const paymentGatewayNames = (order.paymentGatewayNames ?? []).filter(
     (n) => typeof n === "string" && n.trim().length > 0,
   );
@@ -132,6 +138,7 @@ export function composeInvoice({
     notices,
     paid,
     paymentStatus,
+    requiresPayment,
     paymentGatewayNames,
     orderName: order.name,
     separateShippingAddress,