build: modernize Gradle to AGP 8.5 with wrapper and namespace

build.gradle

@@ -1,19 +1,6 @@
-// Top-level build file where you can add configuration options common to all sub-projects/modules.
+// Top-level build file. Plugin versions are declared in settings.gradle
+// (pluginManagement), which is where AGP 8.x expects them.
 
-buildscript {
-    repositories {
-        jcenter()
-    }
-    dependencies {
-        classpath 'com.android.tools.build:gradle:1.+'
-
-        // NOTE: Do not place your application dependencies here; they belong
-        // in the individual module build.gradle files
-    }
-}
-
-allprojects {
-    repositories {
-        jcenter()
-    }
+plugins {
+    id 'com.android.application' version '8.5.2' apply false
 }