basic csv loader, transaction list & half done stats page

lib/domains/account/models/transaction_value.dart

@@ -0,0 +1,23 @@
+import 'package:formz/formz.dart';
+
+enum TransactionValueValidationError {
+  empty('Value empty'),
+  invalid('Value invalid');
+
+  final String message;
+  const TransactionValueValidationError(this.message);
+}
+
+class TransactionValue extends FormzInput<double, TransactionValueValidationError> {
+  const TransactionValue.pure() : super.pure(0);
+  const TransactionValue.dirty([super.value = 0]) : super.dirty();
+
+  @override
+  TransactionValueValidationError? validator(double value) {
+    return value.isNaN
+      ? TransactionValueValidationError.empty
+      : value.isInfinite
+        ? TransactionValueValidationError.invalid
+        : null;
+  }
+}