Android: Add Androidx splash screen to wait for directory initialization

Source/Android/app/src/main/res/values/colors.xml

@@ -4,6 +4,8 @@
     <color name="dolphin_blue_secondary">#21b0f3</color>
     <color name="dolphin_white">#ffffff</color>
 
+    <color name="dolphin_surface">#FDFCFF</color>
+
     <color name="tv_card_unselected">#444444</color>
 
     <color name="invalid_setting_overlay">#36ff0000</color>

Source/Android/app/src/main/res/values/themes.xml

@@ -1,5 +1,11 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
+    <style name="Theme.Dolphin.Splash" parent="Theme.SplashScreen">
+        <item name="windowSplashScreenBackground">@color/dolphin_surface</item>
+        <item name="windowSplashScreenAnimatedIcon">@drawable/ic_dolphin</item>
+        <item name="postSplashScreenTheme">@style/Theme.Dolphin.Main</item>
+    </style>
+
     <!-- Base theme -->
     <style name="Theme.Dolphin.Main" parent="Theme.Material3.DayNight.NoActionBar">
         <item name="colorSurface">@color/dolphin_blue</item>