Refactor VsumTabs component to remove loading state management

- Eliminated loadingId state and its associated logic to simplify the component's functionality.
- Streamlined error handling by removing unnecessary finalization steps.

Author: TsotneMikadze

src/components/ui/VsumTabs.tsx

@@ -43,16 +43,13 @@ export const VsumTabs: React.FC<VsumTabsProps> = ({ openVsums, activeVsumId, onA
 
   useEffect(() => {
     const fetchDetails = async (id: number) => {
-      setLoadingId(id);
       setError('');
       try {
         const res = await apiService.getVsumDetails(id);
         setDetailsById(prev => ({ ...prev, [id]: res.data }));
         setEdits(prev => ({ ...prev, [id]: { name: res.data.name, metaModelIds: (res.data.metaModels || []).map(m => m.id) } }));
       } catch (e) {
         setError(e instanceof Error ? e.message : 'Failed to load vSUM details');
-      } finally {
-        setLoadingId(null);
       }
     };
     if (activeVsumId && !detailsById[activeVsumId]) {