chore: Update Android NDK and enable desugaring

Updates the Android NDK version to 27.0.12077973 and enables core library desugaring for Java 11 compatibility.

Also includes minor formatting changes in `app_router.gr.dart`.

Author: xsahil03x

sample_app/android/app/build.gradle.kts

@@ -8,22 +8,20 @@ plugins {
 android {
     namespace = "io.getstream.feeds.flutter.sample"
     compileSdk = flutter.compileSdkVersion
-    ndkVersion = flutter.ndkVersion
+    ndkVersion = "27.0.12077973"
 
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_11
         targetCompatibility = JavaVersion.VERSION_11
+        isCoreLibraryDesugaringEnabled = true
     }
 
     kotlinOptions {
         jvmTarget = JavaVersion.VERSION_11.toString()
     }
 
     defaultConfig {
-        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId = "io.getstream.feeds.flutter.sample"
-        // You can update the following values to match your application needs.
-        // For more information, see: https://flutter.dev/to/review-gradle-config.
         minSdk = flutter.minSdkVersion
         targetSdk = flutter.targetSdkVersion
         versionCode = flutter.versionCode
@@ -42,3 +40,7 @@ android {
 flutter {
     source = "../.."
 }
+
+dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.0.4")
+}