feat(runtime): native platform backends and UI vessels onto main

ui/examples/native-hello-android/app/src/main/res/layout/activity_main.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  activity_main.xml — placeholder layout.
+
+  The el program sets the content view programmatically via ElBridge.setContentView
+  (called from __window_show → el_android_window_show). This layout is not used
+  at runtime but satisfies Gradle's res/ validation checks.
+-->
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical" />

ui/examples/native-hello-android/app/src/main/res/values/strings.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_name">el-native</string>
+</resources>