fix(android): AGP 9.0 no longer supports proguard-android.txt (#684)

Replace getDefaultProguardFile('proguard-android.txt') with getDefaultProguardFile('proguard-android-optimize.txt') in android/build.gradle.

proguard-android.txt is no longer supported in AGP 9+ since it includes -dontoptimize, which prevents R8 from performing optimizations. This causes a build failure for projects using Android Gradle Plugin 9.x.

See https://capawesome.io/blog/how-to-fix-capacitor-plugin-build-errors-with-agp-9/

Author: VIXI0

android/build.gradle

@@ -33,7 +33,7 @@ android {
     buildTypes {
         release {
             minifyEnabled false
-            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
         }
     }
     lintOptions {