feat: support custom maintenance mode duration

src/widgets/DevicesTable/VehicleSessionsModal.tsx

@@ -21,7 +21,7 @@ interface VehicleSessionsModalProps {
   onClose: () => void;
 }
 
-const formatDateTime = (value: string) => {
+const formatDateTime = (value?: string | null) => {
   if (!value) return "-";
 
   const date = new Date(value);
@@ -38,8 +38,8 @@ const formatDateTime = (value: string) => {
   }).format(date);
 };
 
-const formatDuration = (durationSeconds: number) => {
-  if (!Number.isFinite(durationSeconds) || durationSeconds < 0) {
+const formatDuration = (durationSeconds?: number | null) => {
+  if (durationSeconds == null || !Number.isFinite(durationSeconds) || durationSeconds < 0) {
     return "-";
   }
 
@@ -152,10 +152,10 @@ export const VehicleSessionsModal = observer(
                             {formatDateTime(session.started_at)}
                           </TableCell>
                           <TableCell>
-                            {formatDateTime(session.ended_at)}
+                            {session.ended_at ? formatDateTime(session.ended_at) : "В процессе"}
                           </TableCell>
                           <TableCell align="right">
-                            {formatDuration(session.duration_seconds)}
+                            {session.ended_at ? formatDuration(session.duration_seconds) : "—"}
                           </TableCell>
                         </TableRow>
                       ))}