Add Apple Reminders integration for grocery list with local mapping persistence

Introduce a GroceryListManager facade that delegates to either the existing
in-app GroceryList or a new RemindersGroceryStore backed by EventKit. Users
choose the mode in Settings; when Reminders mode is active the Grocery List
tab is hidden. Recipe-to-reminder grouping uses a local mapping file
(reminder_mappings.data) instead of polluting the reminder's notes field,
with automatic pruning when reminders are deleted externally.

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

Nextcloud Cookbook iOS Client/Views/MainView.swift

@@ -9,12 +9,14 @@ import SwiftUI
 
 struct MainView: View {
     @StateObject var appState = AppState()
-    @StateObject var groceryList = GroceryList()
+    @StateObject var groceryList = GroceryListManager()
 
     // Tab ViewModels
     @StateObject var recipeViewModel = RecipeTabView.ViewModel()
     @StateObject var searchViewModel = SearchTabView.ViewModel()
 
+    @ObservedObject private var userSettings = UserSettings.shared
+
     @State private var selectedTab: Tab = .recipes
 
     enum Tab {
@@ -37,13 +39,23 @@ struct MainView: View {
                     .environmentObject(groceryList)
             }
 
-            SwiftUI.Tab("Grocery List", systemImage: "storefront", value: .groceryList) {
-                GroceryListTabView()
-                    .environmentObject(groceryList)
+            if userSettings.groceryListMode != GroceryListMode.appleReminders.rawValue {
+                SwiftUI.Tab("Grocery List", systemImage: "storefront", value: .groceryList) {
+                    GroceryListTabView()
+                        .environmentObject(groceryList)
+                }
             }
         }
         .tabViewStyle(.sidebarAdaptable)
         .modifier(TabBarMinimizeModifier())
+        .onChange(of: userSettings.groceryListMode) { _, newValue in
+            if newValue == GroceryListMode.appleReminders.rawValue && selectedTab == .groceryList {
+                selectedTab = .recipes
+            }
+            Task {
+                await groceryList.load()
+            }
+        }
         .task {
             recipeViewModel.presentLoadingIndicator = true
             await appState.getCategories()