NEW: MIH Calculator Provider Setup

Frontend/lib/mih_components/mih_providers/mih_calculator_provider.dart

@@ -0,0 +1,21 @@
+import 'package:flutter/foundation.dart';
+
+class MihCalculatorProvider extends ChangeNotifier {
+  List<String> availableCurrencies;
+  int toolIndex;
+
+  MihCalculatorProvider({
+    this.availableCurrencies = const [],
+    this.toolIndex = 0,
+  });
+
+  void setToolIndex(int index) {
+    toolIndex = index;
+    notifyListeners();
+  }
+
+  void setAvailableCurrencies({required List<String> currencies}) async {
+    availableCurrencies = currencies;
+    notifyListeners();
+  }
+}