feat: complete mealplanner app (backend + frontend + deployment)

.NET 8 backend with Zitadel JWT auth, TheMealDB integration,
weekly meal plan generation, shopping list aggregation.
Vue 3 + Tailwind 4 frontend with dark emerald theme,
manual OIDC PKCE auth, all views implemented.
Multi-stage Dockerfile with nginx reverse proxy.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/Models/CheckedShoppingItem.cs

@@ -0,0 +1,10 @@
+namespace MealPlanner.Models;
+
+public class CheckedShoppingItem
+{
+    public Guid Id { get; set; }
+    public Guid MealPlanId { get; set; }
+    public string ItemName { get; set; } = "";
+    public string UserId { get; set; } = "";
+    public bool IsChecked { get; set; }
+}