feat(android): implement foreground service and notification handling for message synchronization

android/app/src/main/java/com/meshchatx/MeshChatApplication.java

@@ -0,0 +1,53 @@
+package com.meshchatx;
+
+import android.app.Application;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.content.Context;
+import android.os.Build;
+
+import com.chaquo.python.android.PyApplication;
+
+public class MeshChatApplication extends PyApplication {
+    public static final String CHANNEL_ID_MESSAGES = "meshchatx_messages";
+    public static final String CHANNEL_ID_BACKGROUND = "meshchatx_background";
+
+    private static volatile Context appContext;
+
+    public static Context getAppContext() {
+        return appContext;
+    }
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        appContext = getApplicationContext();
+        createNotificationChannels();
+    }
+
+    private void createNotificationChannels() {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
+            return;
+        }
+        NotificationManager nm = getSystemService(NotificationManager.class);
+        if (nm == null) {
+            return;
+        }
+
+        NotificationChannel background = new NotificationChannel(
+            CHANNEL_ID_BACKGROUND,
+            getString(R.string.notification_channel_background_name),
+            NotificationManager.IMPORTANCE_LOW
+        );
+        background.setDescription(getString(R.string.notification_channel_background_desc));
+        nm.createNotificationChannel(background);
+
+        NotificationChannel messages = new NotificationChannel(
+            CHANNEL_ID_MESSAGES,
+            getString(R.string.notification_channel_messages_name),
+            NotificationManager.IMPORTANCE_DEFAULT
+        );
+        messages.setDescription(getString(R.string.notification_channel_messages_desc));
+        nm.createNotificationChannel(messages);
+    }
+}