feat: add buildPdf for cashbox export

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

myteamwallet_backend/src/cashbox-export/cashbox-export.utils.ts

@@ -1,4 +1,6 @@
 import { Team } from 'src/teams/entities/team.entity';
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const PDFDocument = require('pdfkit');
 
 export interface CashboxExportRow {
   date: string;
@@ -100,3 +102,35 @@ export function buildCsv(rows: CashboxExportRow[]): string {
   }
   return lines.join('\r\n');
 }
+
+export function buildPdf(
+  team: Pick<Team, 'name'>,
+  rows: CashboxExportRow[],
+  from: string,
+  to: string,
+): Promise<Buffer> {
+  return new Promise((resolve, reject) => {
+    const doc = new PDFDocument({ margin: 40 });
+    const chunks: Buffer[] = [];
+    doc.on('data', (chunk) => chunks.push(chunk));
+    doc.on('end', () => resolve(Buffer.concat(chunks)));
+    doc.on('error', reject);
+
+    doc.fontSize(16).text(`Kassenbuch ${team.name}`);
+    doc.fontSize(10).text(`Zeitraum: ${from} bis ${to}`);
+    doc.moveDown();
+
+    if (rows.length === 0) {
+      doc.text('Keine Buchungen im gewählten Zeitraum.');
+    } else {
+      for (const row of rows) {
+        doc.text(
+          `${row.date.slice(0, 10)}  ${TYPE_LABELS[row.type] ?? row.type}  ${row.who}  ${row.note}  ` +
+            `${formatGermanAmount(row.amount)} €  Saldo: ${formatGermanAmount(row.runningTotal)} €`,
+        );
+      }
+    }
+
+    doc.end();
+  });
+}