fix: prevent creating multiple mainactivity instance

Author: nichbar

app/src/main/AndroidManifest.xml

@@ -36,6 +36,7 @@
         <activity
             android:name=".MainActivity"
             android:exported="true"
+            android:launchMode="singleTask"
             android:theme="@style/Theme.Ulmaridae">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />