feat(eims): printable receipt PDF with RRN and QR

eims-receipt-document.mapper.ts maps an EimsReceipt onto the shared
InvoiceDocumentModel layout, reading amounts back out of the stored request
body. Refuses to render anything not REGISTERED. GET
invoices/:id/eims/receipts/:receiptId/document, scoped to the invoice.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/edr-freight-api/src/modules/eims/eims-receipt-document.mapper.ts

@@ -0,0 +1,107 @@
+import { Invoice } from "../billing/entities/invoice.entity";
+import {
+  InvoiceDocumentModel,
+  pngDataUrl,
+} from "../billing/documents/invoice-document.service";
+import { EimsReceipt, EimsReceiptStatus } from "./entities/eims-receipt.entity";
+import { EimsSalesReceiptRequest, EimsWithholdReceiptRequest } from "./eims-receipt.types";
+
+/**
+ * Maps a filed `EimsReceipt` onto the shared invoice/receipt document layout — mirrors
+ * `eims-invoice.mapper.ts`'s role for `/v1/register`: a pure function, no I/O.
+ *
+ * The amounts (collected amount, mode of payment, withholding amount) live only in
+ * `receipt.request` — the exact body this app sent, typed and written in exactly one place
+ * (`EimsReceiptService`). Reading it back is a cast, not a new source of truth; real columns
+ * would mean a migration + backfill for data already present in a stable shape.
+ *
+ * Throws rather than returning a model for anything not actually filed: a sealed, stamped PDF
+ * for a receipt MoR rejected, never acknowledged, or whose request was somehow never recorded
+ * would read as a genuine tax document. Callers (`EimsReceiptService.document`) let this throw
+ * surface as a 400 — there is nothing sensible to render instead.
+ */
+export function toReceiptDocumentModel(receipt: EimsReceipt, invoice: Invoice): InvoiceDocumentModel {
+  if (receipt.status !== EimsReceiptStatus.Registered) {
+    throw new Error(
+      `Receipt ${receipt.receiptNumber} is ${receipt.status}, not REGISTERED — refusing to print an unfiled receipt.`,
+    );
+  }
+  if (!receipt.request) {
+    throw new Error(`Receipt ${receipt.receiptNumber} has no stored request body — cannot render its amounts.`);
+  }
+
+  const isSales = receipt.kind === "SALES";
+
+  if (isSales) {
+    const req = receipt.request as unknown as EimsSalesReceiptRequest;
+    return build(receipt, invoice, {
+      title: "Sales Receipt",
+      currency: req.ReceiptCurrency,
+      amountLabel: "Collected",
+      lineDescription: `Payment received against invoice ${invoice.invoiceNumber}`,
+      amount: req.CollectedAmount,
+      // A sales receipt is a real payment — this is the one case the shared layout's own default
+      // ("EDR PAID" for kind RECEIPT) is already correct, but set it explicitly so it never drifts
+      // if that default changes for an unrelated reason.
+      sealText: "EDR PAID",
+      extraSummary: [{ label: "Mode of payment", value: req.TransactionDetails.ModeOfPayment }],
+    });
+  }
+
+  const req = receipt.request as unknown as EimsWithholdReceiptRequest;
+  return build(receipt, invoice, {
+    title: "Withholding Receipt",
+    currency: req.InvoiceDetail.Currency,
+    amountLabel: "Withheld",
+    lineDescription: `Withholding (${req.WithholdDetail.Type}) against invoice ${invoice.invoiceNumber}`,
+    amount: req.WithholdDetail.WithholdingAmount,
+    // A withholding receipt is not a payment — the shared layout's "EDR PAID" default would be
+    // wrong here, so this is the one case that MUST override it.
+    sealText: "EDR",
+    extraSummary: [{ label: "Withholding type", value: req.WithholdDetail.Type }],
+  });
+}
+
+function build(
+  receipt: EimsReceipt,
+  invoice: Invoice,
+  opts: {
+    title: string;
+    currency: string;
+    amountLabel: string;
+    lineDescription: string;
+    amount: number;
+    sealText: string;
+    extraSummary: Array<{ label: string; value: string | null }>;
+  },
+): InvoiceDocumentModel {
+  return {
+    kind: "RECEIPT",
+    title: opts.title,
+    documentNumber: receipt.receiptNumber,
+    issuedAt: receipt.submittedAt ?? null,
+    status: receipt.status,
+    currency: opts.currency,
+    summary: [
+      { label: "Invoice", value: invoice.invoiceNumber },
+      { label: "Invoice IRN", value: invoice.eimsIrn ?? null },
+      { label: "RRN", value: receipt.rrn ?? null },
+      { label: "Ack status", value: receipt.ackStatus ?? null },
+      ...opts.extraSummary,
+    ],
+    // No line items on a receipt — one synthetic line, since buildHtml renders the line table
+    // unconditionally and an empty `lines: []` would print a header-only empty table.
+    lines: [
+      {
+        description: opts.lineDescription,
+        quantity: 1,
+        unitRate: opts.amount,
+        amount: opts.amount,
+        currency: opts.currency,
+      },
+    ],
+    totals: [{ label: opts.amountLabel, amount: opts.amount, grand: true }],
+    sealText: opts.sealText,
+    qrImageUrl: receipt.qr ? pngDataUrl(receipt.qr) : null,
+  };
+}