Frontend first draft

frontend/pweb/lib/services/balance.dart

@@ -0,0 +1,22 @@
+abstract class BalanceService {
+  Future<double> getBalance();
+  Future<String> getWalletName();
+  Future<String> getWalletId();
+}
+
+class MockBalanceService implements BalanceService {
+  @override
+  Future<double> getBalance() async {
+    return 3000000.56;
+  }
+
+  @override
+  Future<String> getWalletName() async {
+    return "Wallet";
+  }
+
+  @override
+  Future<String> getWalletId() async {
+    return "WA-12345667";
+  }
+}