Build exchange workspace and shared transaction services (#28)

frontend/app/test/limits_test.dart

@@ -63,12 +63,14 @@ void main() {
         );
         await tester.pumpAndSettle();
         expect(
-          find.text(locale == 'en' ? 'Used' : 'Использовано'),
+          find.text(
+            locale == 'en' ? 'Used this period' : 'Использовано за период',
+          ),
           findsOneWidget,
         );
         expect(
           find.text(locale == 'en' ? 'Reserved' : 'Зарезервировано'),
-          findsOneWidget,
+          findsNothing,
         );
         expect(
           tester