Initial commit: CookIT recipe collection and week planner

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/recipes/recipe_model_test.dart

@@ -0,0 +1,18 @@
+import 'package:cookit/src/recipes/models/recipe.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('unit keys round-trip through JSON, built-in or own', () {
+    for (final key in ['gram', 'bunch', 'own-1234']) {
+      final line = IngredientLine.fromJson(IngredientLine(amount: 1, unitKey: key, name: 'x').toJson());
+      expect(line.unitKey, key);
+    }
+  });
+
+  test('scaled multiplies amount and range, keeps the rest', () {
+    const line = IngredientLine(amount: 2, amountMax: 3, unitKey: 'tablespoon', name: 'Öl', remark: 'gutes');
+    final half = line.scaled(0.5);
+    expect((half.amount, half.amountMax, half.unitKey, half.name, half.remark), (1, 1.5, 'tablespoon', 'Öl', 'gutes'));
+    expect(const IngredientLine(name: 'Salz').scaled(2).amount, isNull);
+  });
+}