fix(plugin): add defensive scheduler initialization to prevent NullPointerException

- Add null checks and lazy initialization for scheduler in all plugin methods
- Prevents NullPointerException when methods called before load() completes
- Ensures scheduler is available for scheduleDailyNotification, scheduleDailyReminder, cancelDailyReminder, and updateDailyReminder
- Adds structured logging for scheduler initialization events
- Resolves critical runtime error under system stress conditions

Fixes: NullPointerException in DailyNotificationScheduler.scheduleNotification()
Tested: Notification system working correctly under stress with 45+ notifications

android/plugin/src/main/java/com/timesafari/dailynotification/DailyNotificationPlugin.java

@@ -581,6 +581,13 @@ public class DailyNotificationPlugin extends Plugin {
             // Ensure storage is initialized
             ensureStorageInitialized();
             
+            // Ensure scheduler is initialized
+            if (scheduler == null) {
+                Log.w(TAG, "DN|SCHEDULER_NULL initializing_scheduler");
+                alarmManager = (AlarmManager) getContext().getSystemService(Context.ALARM_SERVICE);
+                scheduler = new DailyNotificationScheduler(getContext(), alarmManager);
+            }
+            
             // Validate required parameters
             String time = call.getString("time");
             if (time == null || time.isEmpty()) {
@@ -2009,6 +2016,13 @@ public class DailyNotificationPlugin extends Plugin {
         try {
             Log.d(TAG, "Scheduling daily reminder");
             
+            // Ensure scheduler is initialized
+            if (scheduler == null) {
+                Log.w(TAG, "DN|SCHEDULER_NULL initializing_scheduler");
+                alarmManager = (AlarmManager) getContext().getSystemService(Context.ALARM_SERVICE);
+                scheduler = new DailyNotificationScheduler(getContext(), alarmManager);
+            }
+            
             // Extract reminder options
             String id = call.getString("id");
             String title = call.getString("title");
@@ -2088,6 +2102,13 @@ public class DailyNotificationPlugin extends Plugin {
         try {
             Log.d(TAG, "Cancelling daily reminder");
             
+            // Ensure scheduler is initialized
+            if (scheduler == null) {
+                Log.w(TAG, "DN|SCHEDULER_NULL initializing_scheduler");
+                alarmManager = (AlarmManager) getContext().getSystemService(Context.ALARM_SERVICE);
+                scheduler = new DailyNotificationScheduler(getContext(), alarmManager);
+            }
+            
             String reminderId = call.getString("reminderId");
             if (reminderId == null) {
                 call.reject("Missing reminderId parameter");
@@ -2134,6 +2155,13 @@ public class DailyNotificationPlugin extends Plugin {
         try {
             Log.d(TAG, "Updating daily reminder");
             
+            // Ensure scheduler is initialized
+            if (scheduler == null) {
+                Log.w(TAG, "DN|SCHEDULER_NULL initializing_scheduler");
+                alarmManager = (AlarmManager) getContext().getSystemService(Context.ALARM_SERVICE);
+                scheduler = new DailyNotificationScheduler(getContext(), alarmManager);
+            }
+            
             String reminderId = call.getString("reminderId");
             if (reminderId == null) {
                 call.reject("Missing reminderId parameter");