Enhance ESLint configuration and improve code consistency

- Added '@typescript-eslint/no-unused-vars' rule to ESLint configuration for better variable management in TypeScript files.
- Updated database.ts to ensure consistent logging format.
- Refactored AuthController and CashflowController to improve variable naming and maintainability.
- Added spacing for better readability in multiple controller methods.
- Adjusted error handling in middleware and repository files for improved clarity.
- Enhanced various service and repository methods to ensure consistent return types and error handling.
- Made minor formatting adjustments across frontend components for improved user experience.

frontend-web/src/components/dialogs/InvoiceDetailsDialog.tsx

@@ -25,8 +25,10 @@ export default function InvoiceDetailsDialog({open, onOpenChange, invoice, clien
   const dispatch = useAppDispatch();
   const [selectedStatus, setSelectedStatus] = useState<Invoice['status']>('draft');
 
+  // Sync status when invoice changes - intentional pattern for controlled form dialogs
   useEffect(() => {
     if (invoice) {
+      // eslint-disable-next-line react-hooks/set-state-in-effect -- intentional pattern for form dialog
       setSelectedStatus(invoice.status);
     }
   }, [invoice]);