Restore UnpackAssetsActivity as launcher

MainActivity's onCreateJNI() was crashing with JNI null pointer error.
The native code expects proper initialization flow that starts with
UnpackAssetsActivity, which then launches MainActivity.

Restored original launcher flow:
- UnpackAssetsActivity: launcher (exported=true)
- MainActivity: internal activity (exported=false)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

AndroidManifest.xml

@@ -80,8 +80,12 @@
     <application android:appComponentFactory="androidx.core.app.CoreComponentFactory" android:banner="@string/icon_name_tv_row" android:dataExtractionRules="@xml/backup_android12" android:extractNativeLibs="true" android:fullBackupContent="@xml/backup_legacy" android:hardwareAccelerated="true" android:icon="@string/icon_name_row" android:isGame="true" android:label="@string/app_name" android:largeHeap="true" android:localeConfig="@xml/locale_config" android:name="androidx.multidex.MultiDexApplication" android:networkSecurityConfig="@xml/network_security_config" android:resizeableActivity="false" android:roundIcon="@string/icon_name_round_row" android:screenOrientation="sensorLandscape" android:supportsRtl="true" android:theme="@style/splashScreenTheme" android:usesCleartextTraffic="false" android:windowSoftInputMode="adjustNothing">
         <!-- ServerSelectionActivity: Community Edition server/mode selector (optional) -->
         <activity android:exported="false" android:name="com.firemint.realracing.ServerSelectionActivity" android:screenOrientation="sensorLandscape" android:theme="@style/splashScreenTheme"/>
-        <!-- UnpackAssetsActivity: No longer the launcher, now called by MainActivity -->
+        <!-- UnpackAssetsActivity: Original launcher activity -->
-        <activity android:alwaysRetainTaskState="true" android:configChanges="keyboard|keyboardHidden|orientation|screenSize|smallestScreenSize|uiMode" android:exported="false" android:hardwareAccelerated="true" android:label="@string/app_name" android:launchMode="singleTask" android:name="com.firemint.realracing.UnpackAssetsActivity" android:screenOrientation="sensorLandscape" android:theme="@style/splashScreenTheme">
+        <activity android:alwaysRetainTaskState="true" android:configChanges="keyboard|keyboardHidden|orientation|screenSize|smallestScreenSize|uiMode" android:exported="true" android:hardwareAccelerated="true" android:label="@string/app_name" android:launchMode="singleTask" android:name="com.firemint.realracing.UnpackAssetsActivity" android:screenOrientation="sensorLandscape" android:theme="@style/splashScreenTheme">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
             <intent-filter>
                 <action android:name="com.google.android.apps.plus.VIEW_DEEP_LINK"/>
                 <data android:scheme="vnd.google.deeplink"/>
@@ -91,12 +95,8 @@
                 <category android:name="android.intent.category.BROWSABLE"/>
             </intent-filter>
         </activity>
-        <!-- MainActivity: Main launcher activity -->
+        <!-- MainActivity: Main game activity -->
-        <activity android:alwaysRetainTaskState="true" android:configChanges="keyboard|keyboardHidden|orientation|screenSize|smallestScreenSize|uiMode" android:exported="true" android:hardwareAccelerated="true" android:label="@string/app_name" android:launchMode="singleTask" android:name="com.firemint.realracing.MainActivity" android:screenOrientation="sensorLandscape" android:theme="@style/splashScreenTheme">
+        <activity android:alwaysRetainTaskState="true" android:configChanges="keyboard|keyboardHidden|orientation|screenSize|smallestScreenSize|uiMode" android:exported="false" android:hardwareAccelerated="true" android:label="@string/app_name" android:launchMode="singleTask" android:name="com.firemint.realracing.MainActivity" android:screenOrientation="sensorLandscape" android:theme="@style/splashScreenTheme">
-            <intent-filter>
-                <action android:name="android.intent.action.MAIN"/>
-                <category android:name="android.intent.category.LAUNCHER"/>
-            </intent-filter>
         </activity>
         <activity android:name="com.firemint.realracing.SettingsActivity" android:label="RR3 Settings" android:theme="@android:style/Theme.Black.NoTitleBar" android:screenOrientation="portrait"/>
         <property android:name="android.adservices.AD_SERVICES_CONFIG" android:resource="@xml/gma_ad_services_config"/>