feat: proširi prikaz dizalice i vlasnika u zadacima

Dodaj detalje dizalice (proizvođač, model i SN) te vlasnika u modal radnog zadatka i kalendar zadataka, uz zajednički frontend helper za DRY prikaz.

Proširi Task API serializer dodatnim poljima za prikaz dizalice/vlasnika i ažuriraj testove serializera za nova izlazna polja.

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

frontend/src/components/dashboard/TaskCalendarWidget.jsx

@@ -1,6 +1,7 @@
 import { useMemo, useState } from 'preact/hooks';
 import { getStatusLabel } from '../../stores/taskStore';
 import LeftSlideDrawer from '../layout/LeftSlideDrawer';
+import { getTaskCraneKind, getTaskCraneOwner, getTaskCraneSerial } from '../../lib/taskCraneDisplay';
 
 const WEEKDAY_LABELS = ['Po', 'Ut', 'Sr', 'Če', 'Pe', 'Su', 'Ne'];
 const MONTH_NAMES = [
@@ -242,6 +243,9 @@ export default function TaskCalendarWidget({ tasks = [], notes = [], onTaskClick
                                                                 {task.assigned_to_name || '-'} •{' '}
                                                                 {getStatusLabel(task.status || '-')}
                                                             </span>
+                                                            <span className="mt-0.5 block text-[11px] text-text-muted">
+                                                                {getTaskCraneSerial(task)} • {getTaskCraneKind(task)} • {getTaskCraneOwner(task)}
+                                                            </span>
                                                         </button>
                                                     </li>
                                                 ))}