Integrate local notifications scheduler for reminders

docs/SETUP.md

@@ -46,16 +46,28 @@ flutter run --dart-define=ENABLE_BACKGROUND_SYNC=false
 
 ## Reminder Delivery Scaffold
 
-Reminder scheduling is now wired through `ReminderScheduler` and reconciled from
-`LocalRepository` on startup/state changes.
+Reminder scheduling is now wired through `ReminderScheduler` and reconciled
+from `LocalRepository` on startup/state changes.
 
-Current default implementation is no-op:
+Default implementation now uses local notifications runtime where supported.
 
-- `NoopReminderScheduler` in
-  `lib/features/reminders/scheduling/reminder_scheduler.dart`
+Control flag:
 
-This keeps behavior stable across all platforms until real local notification
-integration is added.
+```bash
+flutter run --dart-define=ENABLE_LOCAL_NOTIFICATIONS=true
+```
+
+Disable notifications explicitly:
+
+```bash
+flutter run --dart-define=ENABLE_LOCAL_NOTIFICATIONS=false
+```
+
+Behavior notes:
+
+- web: no-op fallback
+- linux: schedule fallback (no-op) due platform scheduling limitations in plugin
+- android/iOS/macOS/windows: scheduled local notifications
 
 ## Local Persistence Backend