feat: Add User and UserBalance models with serialization methods

feat: Implement BalanceRepository for group balance calculations

feat: Create ExpenseRepository for managing expenses

feat: Add services for handling expenses and storage operations

fix: Update import paths for models in repositories and services

refactor: Rename CountContent to AccountContent in HomePage

chore: Add StorageService for image upload and management

lib/pages/home.dart

@@ -58,7 +58,7 @@ class _HomePageState extends State<HomePage> {
         page = const GroupContent();
         break;
       case 4:
-        page = const CountContent();
+        page = const AccountContent();
         break;
       default:
         page = const HomeContent();