Scaffold native Android build and enforce Rust boundaries (#89)

android/app/src/main/res/values/styles.xml

@@ -0,0 +1,7 @@
+<resources>
+    <style name="Theme.IronStorage" parent="android:style/Theme.Material.Light.NoActionBar">
+        <item name="android:windowLightStatusBar">false</item>
+        <item name="android:statusBarColor">@android:color/transparent</item>
+        <item name="android:windowActionModeOverlay">true</item>
+    </style>
+</resources>