Add cross-device grocery list sync via Nextcloud Cookbook API

Store a _groceryState JSON field on each recipe to track which
ingredients have been added, completed, or removed. Uses per-item
last-writer-wins conflict resolution with ISO 8601 timestamps.
Debounced push (2s) avoids excessive API calls; pull reconciles
on recipe open and app launch. Includes a settings toggle to
enable/disable sync.

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

Nextcloud Cookbook iOS Client/Views/MainView.swift

@@ -81,6 +81,10 @@ struct MainView: View {
                 }
             }
             await groceryList.load()
+            groceryList.configureSyncManager(appState: appState)
+            if UserSettings.shared.grocerySyncEnabled {
+                await groceryList.syncManager?.performInitialSync()
+            }
             recipeViewModel.presentLoadingIndicator = false
         }
     }

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

@@ -12,6 +12,7 @@ import SwiftUI
 
 struct RecipeView: View {
     @EnvironmentObject var appState: AppState
+    @EnvironmentObject var groceryList: GroceryListManager
     @Environment(\.dismiss) private var dismiss
     @StateObject var viewModel: ViewModel
     @GestureState private var dragOffset = CGSize.zero
@@ -75,6 +76,15 @@ struct RecipeView: View {
                     fetchMode: UserSettings.shared.storeImages ? .preferLocal : .onlyServer
                 )
 
+                // Reconcile server grocery state with local data
+                if UserSettings.shared.grocerySyncEnabled {
+                    groceryList.syncManager?.reconcileFromServer(
+                        serverState: viewModel.recipeDetail.groceryState,
+                        recipeId: String(viewModel.recipe.recipe_id),
+                        recipeName: viewModel.recipeDetail.name
+                    )
+                }
+
             } else {
                 // Prepare view for a new recipe
                 if let preloaded = viewModel.preloadedRecipeDetail {

Nextcloud Cookbook iOS Client/Views/SettingsView.swift

@@ -93,10 +93,16 @@ struct SettingsView: View {
                         }
                     }
                 }
+
+                Toggle(isOn: $userSettings.grocerySyncEnabled) {
+                    Text("Sync grocery list across devices")
+                }
             } header: {
                 Text("Grocery List")
             } footer: {
-                if userSettings.groceryListMode == GroceryListMode.appleReminders.rawValue {
+                if userSettings.grocerySyncEnabled {
+                    Text("Grocery list state is synced via your Nextcloud server by storing it alongside recipe data.")
+                } else if userSettings.groceryListMode == GroceryListMode.appleReminders.rawValue {
                     Text("Grocery items will be saved to Apple Reminders. The Grocery List tab will be hidden since you can manage items directly in the Reminders app.")
                 } else {
                     Text("Grocery items are stored locally on this device.")