Initial commit: CookIT recipe collection and week planner

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

test/cooking_mode/cooking_session_test.dart

@@ -0,0 +1,52 @@
+import 'package:cookit/src/cooking_mode/cooking_session.dart';
+import 'package:cookit/src/recipes/models/recipe.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../support/fixtures.dart';
+
+void main() {
+  test('steps run through all Step Sections with continuous numbers', () {
+    final session = CookingSession(
+      recipe(
+        stepSections: const [
+          StepSection(steps: ['Ofen vorheizen.']),
+          StepSection(title: 'Teig', steps: ['Kneten.', 'Ruhen lassen.']),
+        ],
+      ),
+    );
+    expect(
+      [for (final s in session.steps) (s.number, s.section, s.text)],
+      [(1, null, 'Ofen vorheizen.'), (2, 'Teig', 'Kneten.'), (3, 'Teig', 'Ruhen lassen.')],
+    );
+  });
+
+  test('more servings scale every amount', () {
+    final session = CookingSession(recipe()); // 4 servings: 300 g Mehl, 2–3 EL Öl
+    expect(session.factor, 1);
+    session
+      ..moreServings()
+      ..moreServings();
+    expect(session.servings, 6);
+    final lines = session.ingredientGroups.first.lines;
+    expect(lines[0].amount, 450);
+    expect((lines[1].amount, lines[1].amountMax), (3, 4.5));
+  });
+
+  test('servings never go below one and fractional servings step to whole numbers', () {
+    final session = CookingSession(Recipe(id: 'x', name: 'x', servings: 2.5, createdAt: testTime, updatedAt: testTime));
+    session.fewerServings();
+    expect(session.servings, 2);
+    session
+      ..fewerServings()
+      ..fewerServings();
+    expect(session.servings, 1);
+    session.moreServings();
+    expect(session.servings, 2);
+  });
+
+  test('a Recipe without Servings is not scaled', () {
+    final session = CookingSession(Recipe(id: 'x', name: 'x', createdAt: testTime, updatedAt: testTime));
+    expect(session.canScale, isFalse);
+    expect(session.factor, 1);
+  });
+}