Add meal plan feature with cross-device sync and automatic stale data cleanup

Introduces weekly meal planning with a calendar-based tab view, per-recipe
date assignments synced via Nextcloud Cookbook custom metadata, and 30-day
automatic pruning of old entries on load, save, and sync merge.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Nextcloud Cookbook iOS Client/Views/Recipes/RecipeListView.swift

@@ -13,6 +13,7 @@ import SwiftUI
 struct RecipeListView: View {
     @EnvironmentObject var appState: AppState
     @EnvironmentObject var groceryList: GroceryListManager
+    @EnvironmentObject var mealPlan: MealPlanManager
     @State var categoryName: String
     @State var searchText: String = ""
     var onCreateNew: () -> Void
@@ -78,6 +79,7 @@ struct RecipeListView: View {
             RecipeView(viewModel: RecipeView.ViewModel(recipe: recipe))
                 .environmentObject(appState)
                 .environmentObject(groceryList)
+                .environmentObject(mealPlan)
         }
         .toolbar {
             ToolbarItem(placement: .topBarTrailing) {