Add category and recipe sorting with multiple modes and order inversion

Categories on the main page can be sorted by Recently Used, Alphabetical,
or Manual (drag-to-reorder). The sort menu appears inline next to the
Categories header. All Recipes is included in the sort order and manual
reorder sheet. Recipes within category and all-recipes lists can be sorted
by Recently Added or Alphabetical, with the sort button in the toolbar.
All non-manual sort modes support order inversion via a Reverse/Default
Order toggle. Date parsing handles both formatted strings and Unix
timestamps, with recipe_id as fallback when dates are unavailable.

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

Nextcloud Cookbook iOS Client/AppState.swift

@@ -18,6 +18,8 @@ import UIKit
     @Published var timers: [String: RecipeTimer] = [:]
     @Published var categoryImages: [String: UIImage] = [:]
     @Published var recentRecipes: [Recipe] = []
+    @Published var categoryAccessDates: [String: Date] = [:]
+    @Published var manualCategoryOrder: [String] = []
     var recipeImages: [Int: [String: UIImage]] = [:]
     var imagesNeedUpdate: [Int: [String: Bool]] = [:]
     var lastUpdates: [String: Date] = [:]
@@ -347,6 +349,34 @@ import UIKit
         dataStore.delete(path: "recent_recipes.data")
     }
 
+    // MARK: - Category sorting
+
+    func trackCategoryAccess(_ categoryName: String) {
+        categoryAccessDates[categoryName] = Date()
+        Task {
+            await saveLocal(categoryAccessDates, path: "category_access_dates.data")
+        }
+    }
+
+    func loadCategoryAccessDates() async {
+        if let loaded: [String: Date] = await loadLocal(path: "category_access_dates.data") {
+            self.categoryAccessDates = loaded
+        }
+    }
+
+    func updateManualCategoryOrder(_ order: [String]) {
+        manualCategoryOrder = order
+        Task {
+            await saveLocal(manualCategoryOrder, path: "manual_category_order.data")
+        }
+    }
+
+    func loadManualCategoryOrder() async {
+        if let loaded: [String] = await loadLocal(path: "manual_category_order.data") {
+            self.manualCategoryOrder = loaded
+        }
+    }
+
     // MARK: - Data management
 
     func deleteAllData() {