Pin Flutter 3.47.0 (Dart 3.13) as the CI source of truth and move the
Android toolchain to the 3.47 template versions: Gradle 9.3.1, AGP 9.1.0,
Kotlin 2.4.0.
App Gradle script matches the 3.47 template (drop kotlin-android /
kotlinOptions, use compilerOptions). Keep android.builtInKotlin=false and
android.newDsl=false so plugins that still apply KGP keep building.
AGP 9 requires libraries to compile against their dependencies' compileSdk;
force plugin modules to 36 via finalizeDsl. Ignore android/build/, which
AGP 9 now writes a problems report into.
analyze, test, and a release APK all passed. 16 KB zip alignment verified.
iOS UIScene is not in this commit: AppDelegate is customized
(CookieExtractorPlugin), so Flutter will not auto-migrate.