ui fix for shift UI

pages/cart/calendar/index.tsx

@@ -367,6 +367,8 @@ export default function CalendarPage({ initialEvents, initialShifts }) {
             const { data } = await axiosInstance.post("/api/data/assignments", newAssignment);
             // Update the 'publisher' property of the returned data with the full publisher object
             data.publisher = publisher;
+            data.shift = shifts.find(shift => shift.id === shiftId);
+            publisher.assignments = [...publisher.assignments, data];
             handleAssignmentChange(publisher.id, 'add');
         } catch (error) {
             console.error("Error adding assignment:", error);