CalEvent gains `reminders` (parsed from the server); AppSettings/SettingsStore gain `defaultReminderMinutes` (null = off) and it's sent via updateSettings; createLocalEvent/updateLocalEvent/eventBody and CalendarViewModel.saveEvent thread `reminders` through. UI (editor + settings picker) and the local notification scheduling follow next. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>