Initiales HabitTracker-Projekt: SwiftUI + SwiftData Gewohnheiten-Tracker

Natives iOS-App-Gerüst (Xcode 26, synchronisierte Ordner, iOS 18+).

Features:
- Gewohnheiten anlegen (Name, SF-Symbol, Farbe), heute abhaken, Streaks, Löschen
- Detailansicht mit Monatskalender (Tage nachtragbar) und Statistiken
- Tägliche Erinnerungen via lokale Notifications
- Home-Screen-Widget (klein/mittel) mit App-Group-Datenaustausch

HabitTracker/Support/NotificationManager.swift

@@ -0,0 +1,49 @@
+import Foundation
+import UserNotifications
+
+@MainActor
+enum NotificationManager {
+    /// Default reminder time (09:00) used when the user first enables a reminder.
+    static var defaultTime: Date {
+        Calendar.current.date(bySettingHour: 9, minute: 0, second: 0, of: .now) ?? .now
+    }
+
+    @discardableResult
+    static func requestAuthorization() async -> Bool {
+        do {
+            return try await UNUserNotificationCenter.current()
+                .requestAuthorization(options: [.alert, .sound, .badge])
+        } catch {
+            return false
+        }
+    }
+
+    /// Cancels any existing reminder for the habit and, if it has a reminder
+    /// time, schedules a new daily notification.
+    static func reschedule(for habit: Habit) {
+        let center = UNUserNotificationCenter.current()
+        let id = identifier(for: habit)
+        center.removePendingNotificationRequests(withIdentifiers: [id])
+
+        guard let time = habit.reminderTime else { return }
+
+        let content = UNMutableNotificationContent()
+        content.title = habit.name
+        content.body = "Zeit für deine Gewohnheit"
+        content.sound = .default
+
+        let components = Calendar.current.dateComponents([.hour, .minute], from: time)
+        let trigger = UNCalendarNotificationTrigger(dateMatching: components, repeats: true)
+        let request = UNNotificationRequest(identifier: id, content: content, trigger: trigger)
+        center.add(request)
+    }
+
+    static func cancel(for habit: Habit) {
+        UNUserNotificationCenter.current()
+            .removePendingNotificationRequests(withIdentifiers: [identifier(for: habit)])
+    }
+
+    private static func identifier(for habit: Habit) -> String {
+        "habit-\(habit.uuid.uuidString)"
+    }
+}