Show overdue + today task count on app icon badge

updateBadge() counts all incomplete tasks with a due date earlier
than tomorrow (i.e. overdue or due today) and calls setBadgeCount().
Called inside reschedule() so the badge updates on foreground, task
changes, and workout set completions — same triggers as notifications.

Co-Authored-By: Kutesir <tqwyy79vzn@privaterelay.appleid.com>

KisaniCal/Managers/NotificationManager.swift

@@ -51,9 +51,22 @@ final class NotificationManager: NSObject, ObservableObject, @unchecked Sendable
             guard ok else { return }
             self.scheduleWorkout(schedule: schedule, programs: programs, progress: progress)
             self.scheduleTasks(snapshot: tasks)
+            self.updateBadge(snapshot: tasks)
         }
     }
 
+    // MARK: - Badge
+
+    private func updateBadge(snapshot: [TaskItem]) {
+        let startOfDay = Calendar.current.startOfDay(for: Date())
+        let tomorrow   = Calendar.current.date(byAdding: .day, value: 1, to: startOfDay)!
+        let count = snapshot.filter { t in
+            guard !t.isComplete, let due = t.dueDate else { return false }
+            return due < tomorrow  // overdue or due today
+        }.count
+        center.setBadgeCount(count) { _ in }
+    }
+
     // MARK: - Workout reminders + check-in
 
     private func scheduleWorkout(schedule: [Int: UUID], programs: [WorkoutProgram], progress: Double) {