fix: remove kotlin-android plugin for AGP 9 built-in Kotlin support

android/app/build.gradle.kts

@@ -3,7 +3,6 @@ import java.io.FileInputStream
 
 plugins {
     id("com.android.application")
-    id("kotlin-android")
     // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
     id("dev.flutter.flutter-gradle-plugin")
 }

android/settings.gradle.kts

@@ -20,7 +20,6 @@ pluginManagement {
 plugins {
     id("dev.flutter.flutter-plugin-loader") version "1.0.0"
     id("com.android.application") version "9.0.0" apply false
-    id("org.jetbrains.kotlin.android") version "2.3.10" apply false
 }
 
 include(":app")