カレンダーイベント管理アプリの最初のプロジェクト構成と基本実装

- .gitignore や project.yml、Makefile などによる基本的なプロジェクト構成ファイルを追加
- macOSカレンダーイベントを表示するSwiftUIアプリの主要コンポーネント（イベント取得・リスト・カレンダー設定画面など）を実装
- カレンダーの表示期間や「今日へスクロール」「設定画面」遷移などの基本動作に対応

Sources/CalendarService.swift

@@ -0,0 +1,70 @@
+import EventKit
+import Foundation
+
+class CalendarService: ObservableObject {
+    private let eventStore = EKEventStore()
+    @Published var events: [EKEvent] = []
+    @Published var selectedCalendars: Set<String> = []
+    @Published var availableCalendars: [EKCalendar] = []
+    @Published var hasAccess = false
+
+    init() {
+        Task {
+            await requestAccess()
+        }
+    }
+
+    @MainActor
+    func requestAccess() async {
+        do {
+            let granted = try await eventStore.requestFullAccessToEvents()
+            hasAccess = granted
+            if granted {
+                loadCalendars()
+                loadDefaultSelectedCalendars()
+                loadEvents()
+            }
+        } catch {
+            print("Calendar access error: \(error)")
+            hasAccess = false
+        }
+    }
+
+    @MainActor
+    func loadCalendars() {
+        availableCalendars = eventStore.calendars(for: .event)
+    }
+
+    @MainActor
+    func loadDefaultSelectedCalendars() {
+        if let savedCalendars = UserDefaults.standard.array(forKey: "selectedCalendars") as? [String] {
+            selectedCalendars = Set(savedCalendars)
+        } else {
+            selectedCalendars = Set(availableCalendars.map { $0.calendarIdentifier })
+        }
+    }
+
+    @MainActor
+    func saveSelectedCalendars() {
+        UserDefaults.standard.set(Array(selectedCalendars), forKey: "selectedCalendars")
+        loadEvents()
+    }
+
+    @MainActor
+    func loadEvents() {
+        let calendar = Calendar.current
+        let today = calendar.startOfDay(for: Date())
+
+        guard let startDate = calendar.date(byAdding: .day, value: -14, to: today),
+              let endDate = calendar.date(byAdding: .day, value: 14, to: today) else {
+            return
+        }
+
+        let calendars = availableCalendars.filter { selectedCalendars.contains($0.calendarIdentifier) }
+
+        let predicate = eventStore.predicateForEvents(withStart: startDate, end: endDate, calendars: calendars)
+        let fetchedEvents = eventStore.events(matching: predicate)
+
+        events = fetchedEvents.sorted { $0.startDate < $1.startDate }
+    }
+}