feat: add meal planning feature with API integration

- Introduced MealPlanApiPaths for handling meal plan related API endpoints.
- Added MealPlanScreen for displaying and managing meal plans.
- Implemented MealPlanRepository for fetching and updating meal plan data.
- Created data models: MealPlanEntry, MealPlanRecipe, InventoryCompareItem, ShoppingItem, and MealPlanDashboard.
- Integrated meal plan functionality into the app router and UI.
- Updated localization files for meal plan related strings in English and Swedish.
- Added state management for meal plan using Riverpod.

flutter/lib/features/meal_plan/domain/meal_plan_week.dart

@@ -0,0 +1,34 @@
+import 'package:intl/intl.dart';
+
+class MealPlanWeek {
+  final DateTime start;
+  final List<DateTime> days;
+
+  const MealPlanWeek({
+    required this.start,
+    required this.days,
+  });
+
+  factory MealPlanWeek.fromOffset(int offset) {
+    final now = DateTime.now();
+    final today = DateTime(now.year, now.month, now.day);
+    final monday = today.subtract(Duration(days: today.weekday - 1)).add(
+          Duration(days: offset * 7),
+        );
+
+    return MealPlanWeek(
+      start: monday,
+      days: List.generate(
+        7,
+        (index) => DateTime(monday.year, monday.month, monday.day + index),
+      ),
+    );
+  }
+
+  DateTime get end => days.last;
+
+  String get fromIso => isoDate(start);
+  String get toIso => isoDate(end);
+
+  String isoDate(DateTime date) => DateFormat('yyyy-MM-dd').format(date);
+}