fix: export filtered tender list as real XLSX

src/services/tenderWorkbook.js

@@ -0,0 +1,21 @@
+// User/source text stays a string cell, including leading '=' and embedded newlines.
+export async function createTenderWorkbook(tenders) {
+  if (!Array.isArray(tenders) || !tenders.length) throw new Error('Dışa aktarılacak ihale bulunamadı.');
+  const {default:ExcelJS} = await import('exceljs');
+  const book = new ExcelJS.Workbook();
+  book.creator = 'İhaleist';
+  const sheet = book.addWorksheet('İhale Listesi');
+  sheet.columns = [
+    ['İKN',20],['Başlık',65],['Kurum',45],['Şehir',20],['İhale tarihi',18],
+    ['İhale saati',15],['Alım türü',25],['Sektör',30],['CPV',35],['Kaynak',55],
+  ].map(([header,width])=>({header,width}));
+  for (const t of tenders) {
+    sheet.addRow([t.ikn,t.baslik,t.kurum,t.sehir,t.tarih,t.saat,t.alimTuru,t.sektor,
+      t.cpvLabel || (Array.isArray(t.cpv) ? t.cpv.join(', ') : t.cpv),t.kaynakUrl].map(v=>String(v ?? '')));
+  }
+  sheet.views = [{state:'frozen',ySplit:1}];
+  sheet.autoFilter = {from:'A1',to:`J${tenders.length+1}`};
+  sheet.getRow(1).font = {bold:true};
+  sheet.eachRow(row=>{row.alignment={vertical:'top',wrapText:true};});
+  return book.xlsx.writeBuffer();
+}