feat: add buildCsv for cashbox export

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

@@ -60,3 +60,41 @@ export function buildRows(team: Team, from: string, to: string): CashboxExportRo
     return { ...row, runningTotal };
   });
 }
+
+const TYPE_LABELS: Record<string, string> = {
+  payment: 'Zahlung',
+  credit: 'Guthaben',
+  expense: 'Ausgabe',
+};
+
+function formatGermanAmount(value: number): string {
+  return value.toFixed(2).replace('.', ',');
+}
+
+function escapeCsvField(value: string): string {
+  if (/[;"\n\r]/.test(value)) {
+    return `"${value.replace(/"/g, '""')}"`;
+  }
+  return value;
+}
+
+export function buildCsv(rows: CashboxExportRow[]): string {
+  const lines = ['Datum;Typ;Wer;Notiz;Betrag;Periodensaldo'];
+  if (rows.length === 0) {
+    lines.push('Keine Buchungen im gewählten Zeitraum');
+  } else {
+    for (const row of rows) {
+      lines.push(
+        [
+          row.date.slice(0, 10),
+          TYPE_LABELS[row.type] ?? row.type,
+          escapeCsvField(row.who),
+          escapeCsvField(row.note),
+          formatGermanAmount(row.amount),
+          formatGermanAmount(row.runningTotal),
+        ].join(';'),
+      );
+    }
+  }
+  return lines.join('\r\n');
+}