feat: dodaj mjesecni izvjestaj servisera i troskova u kalendar widget

- Dva nova Django API endpointa (GET /api/fleet/reports/monthly-servicer/ i
  /api/fleet/reports/monthly-costs/) koji generiraju DOCX u A4 landscape formatu
- TaskCalendarWidget prosiren s report panelom: dva gumba iznad kalendara
  (Izvjestaj servisera / Izvjestaj troskova) sirenjem drawer-a na 680 px
- Preview tablice s podacima iz postojeceg tasks/workOrders store-a
- downloadMonthlyServiserReport i downloadMonthlyCostsReport u store-u
- TaskCalendarPortal prosljeduje activeWorkOrders prop widgetu

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/src/stores/fleetDashboardStore.js

@@ -913,6 +913,34 @@ export async function downloadWorkOrderInvoicesDocx(workOrderId) {
     }
 }
 
+export async function downloadMonthlyServiserReport(year, month) {
+    try {
+        const blob = await api.get(
+            `fleet/reports/monthly-servicer/?year=${year}&month=${month}`,
+            { responseType: 'blob' },
+        );
+        saveBlobToFile(blob, `izvjestaj-servisera-${year}-${String(month).padStart(2, '0')}.docx`);
+        showToast('Izvještaj servisera je preuzet.', 'success');
+    } catch (err) {
+        showToast(err?.message || 'Preuzimanje izvještaja servisera nije uspjelo.', 'error');
+        throw err;
+    }
+}
+
+export async function downloadMonthlyCostsReport(year, month) {
+    try {
+        const blob = await api.get(
+            `fleet/reports/monthly-costs/?year=${year}&month=${month}`,
+            { responseType: 'blob' },
+        );
+        saveBlobToFile(blob, `troskovi-servisera-${year}-${String(month).padStart(2, '0')}.docx`);
+        showToast('Izvještaj troškova je preuzet.', 'success');
+    } catch (err) {
+        showToast(err?.message || 'Preuzimanje izvještaja troškova nije uspjelo.', 'error');
+        throw err;
+    }
+}
+
 export async function downloadGeneratedPdfByUrl(downloadUrl, filename = 'document.pdf') {
     if (!downloadUrl) {
         showToast('Nedostaje URL za preuzimanje PDF-a.', 'error');