Fix meal plan not populating on first login and add pull-to-refresh sync

Rewrite MealPlanSyncManager.performSync() (renamed from performInitialSync) to
discover _mealPlanAssignment metadata from all server recipes, not just locally-
known ones. On first sync all recipes are checked; on subsequent syncs only
recipes modified since lastMealPlanSyncDate are fetched (max 5 concurrent).

Trigger meal plan sync from pull-to-refresh on both the recipe and meal plan
tabs, and from the "Refresh all" toolbar button.

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

Nextcloud Cookbook iOS Client/Views/Tabs/MealPlanTabView.swift

@@ -73,6 +73,15 @@ struct MealPlanTabView: View {
                 }
             }
             .navigationTitle("Meal Plan")
+            .refreshable {
+                await appState.getCategories()
+                for category in appState.categories {
+                    await appState.getCategory(named: category.name, fetchMode: .preferServer)
+                }
+                if UserSettings.shared.mealPlanSyncEnabled {
+                    await mealPlan.syncManager?.performSync()
+                }
+            }
             .navigationDestination(for: Recipe.self) { recipe in
                 RecipeView(viewModel: RecipeView.ViewModel(recipe: recipe))
                     .environmentObject(appState)