feat: add macOS task board widget app

UTrello/Shared/TaskItem.swift

@@ -0,0 +1,31 @@
+import Foundation
+
+enum TaskList: String, CaseIterable, Codable, Identifiable {
+    case todo
+    case doing
+    case done
+
+    var id: String { rawValue }
+
+    var title: String {
+        switch self {
+        case .todo: "To do"
+        case .doing: "Doing"
+        case .done: "Done"
+        }
+    }
+}
+
+struct TaskItem: Identifiable, Codable, Equatable {
+    let id: UUID
+    var title: String
+    var list: TaskList
+    let createdAt: Date
+
+    init(id: UUID = UUID(), title: String, list: TaskList = .todo, createdAt: Date = .now) {
+        self.id = id
+        self.title = title
+        self.list = list
+        self.createdAt = createdAt
+    }
+}

UTrello/Shared/TaskStore.swift

@@ -0,0 +1,53 @@
+import Foundation
+import Combine
+#if canImport(WidgetKit)
+import WidgetKit
+#endif
+
+final class TaskStore: ObservableObject {
+    static let groupIdentifier = "group.com.example.utrello"
+    private static let tasksKey = "tasks"
+
+    @Published private(set) var tasks: [TaskItem] {
+        didSet { save() }
+    }
+
+    init() {
+        tasks = Self.loadTasks()
+    }
+
+    func add(title: String, to list: TaskList = .todo) {
+        let title = title.trimmingCharacters(in: .whitespacesAndNewlines)
+        guard !title.isEmpty else { return }
+        tasks.insert(TaskItem(title: title, list: list), at: 0)
+    }
+
+    func move(_ task: TaskItem, to list: TaskList) {
+        guard let index = tasks.firstIndex(of: task) else { return }
+        tasks[index].list = list
+    }
+
+    func delete(_ task: TaskItem) {
+        tasks.removeAll { $0.id == task.id }
+    }
+
+    private func save() {
+        guard let data = try? JSONEncoder().encode(tasks) else { return }
+        Self.defaults.set(data, forKey: Self.tasksKey)
+#if canImport(WidgetKit)
+        WidgetCenter.shared.reloadTimelines(ofKind: "UTrelloTasksWidget")
+#endif
+    }
+
+    static func loadTasks() -> [TaskItem] {
+        guard
+            let data = defaults.data(forKey: tasksKey),
+            let tasks = try? JSONDecoder().decode([TaskItem].self, from: data)
+        else { return [] }
+        return tasks
+    }
+
+    private static var defaults: UserDefaults {
+        UserDefaults(suiteName: groupIdentifier) ?? .standard
+    }
+}