usability fixes

lib/screens/accounts/account_provider.dart

@@ -17,6 +17,9 @@ class AccountProvider extends ChangeNotifier {
   String? _accountError;
   String? _statementError;
 
+  /// Cached balances keyed by currency code (e.g. 'USD', 'ZWG').
+  final Map<String, AccountModel?> _balances = {};
+
   AccountModel? get account => _account;
   StatementModel? get statement => _statement;
   bool get isLoadingAccount => _isLoadingAccount;
@@ -25,6 +28,20 @@ class AccountProvider extends ChangeNotifier {
   String? get statementError => _statementError;
   bool _isDisposed = false;
 
+  /// Returns a cached account balance for [currency], or null if not yet
+  /// fetched.
+  AccountModel? balanceForCurrency(String currency) {
+    return _balances[currency.toUpperCase()];
+  }
+
+  /// Returns the account with name 'City Wallet' for [currency], or null.
+  AccountModel? cityWalletBalance() {
+    return _balances.values.firstWhere(
+      (a) => a?.name == 'City Wallet',
+      orElse: () => null,
+    );
+  }
+
   @override
   void notifyListeners() {
     if (!_isDisposed) {
@@ -52,6 +69,7 @@ class AccountProvider extends ChangeNotifier {
       );
 
       _account = AccountModel.fromJson(response);
+      _balances[currency.toUpperCase()] = _account;
       _isLoadingAccount = false;
       notifyListeners();
       return ApiResponse.success(_account!);
@@ -71,6 +89,17 @@ class AccountProvider extends ChangeNotifier {
     }
   }
 
+  /// Pre-load multiple currency balances at once. Results are stored in the
+  /// [_balances] map so any widget can access them later.
+  Future<void> preloadBalances(
+    String? workspaceId,
+    List<String> currencies,
+  ) async {
+    for (final currency in currencies) {
+      await fetchAccount(workspaceId, currency);
+    }
+  }
+
   Future<ApiResponse<StatementModel>> fetchStatement({
     required String workspaceId,
     required String currency,
@@ -117,4 +146,4 @@ class AccountProvider extends ChangeNotifier {
     _statementError = null;
     notifyListeners();
   }
-}
+}