feat: push notifications via WorkManager background polling

- NotificationWorker checks for new notifications every 15 min (WorkManager)
- Shows Android system notifications with Mark Read action
- Notification channels for general + alerts
- Permission request on Android 13+
- Boot persistence via WorkManager
- On-app-open immediate notification check

android/app/src/main/AndroidManifest.xml

@@ -5,6 +5,8 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
     <uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
 
     <application
         android:name=".ServerManagerApp"
@@ -25,6 +27,14 @@
             </intent-filter>
         </activity>
 
+        <receiver
+            android:name=".util.NotificationActionReceiver"
+            android:exported="false">
+            <intent-filter>
+                <action android:name="com.devlab.app.MARK_READ" />
+            </intent-filter>
+        </receiver>
+
         <provider
             android:name="androidx.core.content.FileProvider"
             android:authorities="${applicationId}.fileprovider"