Upgrade to Android Gradle Plugin 9.0.0

- Update AGP 8.13.2 → 9.0.0, Gradle 8.14.3 → 9.1.0
- Migrate kotlin-android/parcelize to full plugin names
- Add buildConfig = true (AGP 9.0 defaults false)
- Migrate deprecated srcDirs() to directories API
- Update gradle-play-publisher 3.12.1 → 3.13.0
- Add android.newDsl=false workaround for play-publisher

gradle.properties

@@ -21,5 +21,7 @@ kotlin.code.style=official
 # resources declared in the library itself and none from the library's dependencies,
 # thereby reducing the size of the R class for that library
 android.nonTransitiveRClass=true
-android.defaults.buildfeatures.buildconfig=true
-android.nonFinalResIds=false
+# Workaround for gradle-play-publisher not supporting AGP 9.0 yet
+# See https://github.com/Triple-T/gradle-play-publisher/issues/1175
+android.newDsl=false
+android.builtInKotlin=false