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/blocs/balance/balance_state.dart

@@ -0,0 +1,40 @@
+import 'package:equatable/equatable.dart';
+import '../../models/group_balance.dart';
+
+abstract class BalanceState extends Equatable {
+  const BalanceState();
+
+  @override
+  List<Object?> get props => [];
+}
+
+class BalanceInitial extends BalanceState {}
+
+class BalanceLoading extends BalanceState {}
+
+class BalanceLoaded extends BalanceState {
+  final GroupBalance groupBalance;
+
+  const BalanceLoaded(this.groupBalance);
+
+  @override
+  List<Object?> get props => [groupBalance];
+}
+
+class BalanceOperationSuccess extends BalanceState {
+  final String message;
+
+  const BalanceOperationSuccess(this.message);
+
+  @override
+  List<Object?> get props => [message];
+}
+
+class BalanceError extends BalanceState {
+  final String message;
+
+  const BalanceError(this.message);
+
+  @override
+  List<Object?> get props => [message];
+}