fix: calculate PREKOVREMENI as total hours minus regular 8h

PREKOVREMENI (overtime hours) is now correctly calculated as the difference between total work+travel hours and the standard 8-hour workday.

frontend/src/components/dashboard/TaskCalendarWidget.jsx

@@ -320,6 +320,8 @@ export default function TaskCalendarWidget({ tasks = [], notes = [], workOrders
                     totalHours += Number(entry.totalHours || 0);
                 }
 
+                const regularHours = 8;
+                const overtimeHours = Math.max(0, totalHours - regularHours);
                 rows.push({
                     key,
                     clickable: false,
@@ -332,8 +334,8 @@ export default function TaskCalendarWidget({ tasks = [], notes = [], workOrders
                         joinUnique(locations) || '-',
                         startTimes.length ? formatTime(new Date(Math.min(...startTimes.map((item) => item.getTime())))) : '-',
                         endTimes.length ? formatTime(new Date(Math.max(...endTimes.map((item) => item.getTime())))) : '-',
-                        '8',
-                        formatHourValue(totalHours, '0'),
+                        formatHourValue(regularHours, '0'),
+                        formatHourValue(overtimeHours, '0'),
                         joinUnique(workOrderLabels) || '-',
                     ],
                 });