Shrink output apk size.

This does reduce it by about 30% . (27M -> 17M)

It could be more effective if there was a way to enable stronger zip compression.
But I haven't been able to find a way to do so yet.

For now maybe distribute the apk gzipped (apk.gz) to improve compression.
This reduces size by about another 50 % (output ~ 8.7M)

android/app/build.gradle.kts

@@ -47,7 +47,8 @@ android {
 
     buildTypes {
         release {
-            isMinifyEnabled = false
+            isMinifyEnabled = true
+            isShrinkResources = true
             proguardFiles(
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro"

android/app/proguard-rules.pro

@@ -18,4 +18,6 @@
 
 # If you keep the line number information, uncomment this to
 # hide the original source file name.
-#-renamesourcefileattribute SourceFile
+#-renamesourcefileattribute SourceFile
+
+-dontwarn org.gradle.api.Plugin