feat: dnevni unosi i svi dani u mjesecnom izvjestaju servisera

- Dodan model MonthlyServicerDayEntry s automatskom popunom prema tipu:
  office (08:00-16:00, Zagreb ured), vacation i sick_leave (8h bez vremena)
- Migracija 0034_monthlyservicerdayentry za novu tablicu s UniqueConstraint
- Novi ViewSet + serializer + endpoint fleet/monthly-servicer-day-entries/
  (upsert: POST za novi dan ili update za isti dan ako vec postoji)
- Backend DOCX report (_build_monthly_servicer_report_rows) sad generira
  redak za SVAKI dan u mjesecu: taskovi > rucni unos > prazan red
- TaskCalendarWidget potpuno prepisan bez mojibake znakova
  (zamjena UTF-8 specijalnih znakova ASCII ekvivalentima u string literalima)
- Tablica izvjestaja servisera: klikom na red bez naloga otvara se overlay
  s tri opcije (Rad u uredu / Bolovanje / Godisnji)
- TaskCalendarPortal: dodan calendarWorkOrders computed (svi statusi)
  kako bi report imao potpune podatke o radnom vremenu
- fetchMonthlyServicerEntries i upsertMonthlyServicerEntry u store-u

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

frontend/src/stores/fleetDashboardStore.js

@@ -913,6 +913,30 @@ export async function downloadWorkOrderInvoicesDocx(workOrderId) {
     }
 }
 
+export async function fetchMonthlyServicerEntries(year, month) {
+    const payload = await api.get(
+        `fleet/monthly-servicer-day-entries/?year=${year}&month=${month}`
+    );
+    return Array.isArray(payload) ? payload : (payload?.results ?? []);
+}
+
+export async function upsertMonthlyServicerEntry(data = {}) {
+    if (!data.entry_date) {
+        throw new Error('Datum dnevnog unosa je obavezan.');
+    }
+    if (!data.entry_type) {
+        throw new Error('Vrsta dnevnog unosa je obavezna.');
+    }
+    try {
+        const response = await api.post('fleet/monthly-servicer-day-entries/', data);
+        showToast('Dnevni unos je uspjesno spremljen.', 'success');
+        return response;
+    } catch (err) {
+        showToast(err?.message || 'Spremanje dnevnog unosa nije uspjelo.', 'error');
+        throw err;
+    }
+}
+
 export async function downloadMonthlyServiserReport(year, month) {
     try {
         const blob = await api.get(