refactor: 重构 schemas 结构，统一枚举定义

apps/android/app/src/main/res/drawable-v21/launch_background.xml

@@ -1,7 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Modify this file to customize your launch splash screen -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:drawable="?android:colorBackground" />
+    <item android:drawable="@color/launchBackground" />
 
     <!-- You can insert your own image assets here -->
     <!-- <item>

apps/android/app/src/main/res/drawable/launch_background.xml

@@ -1,7 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Modify this file to customize your launch splash screen -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:drawable="@android:color/white" />
+    <item android:drawable="@color/launchBackground" />
 
     <!-- You can insert your own image assets here -->
     <!-- <item>

apps/android/app/src/main/res/values/colors.xml

@@ -1,4 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <color name="ic_launcher_background">#FFFFFF</color>
+    <color name="launchBackground">#EFF8FF</color>
 </resources>