build(config): increase gradle heap for release builds

Raise the Gradle heap to 4 GB and cap workers at two so Jetifier and Kotlin release compilation do not exhaust memory while processing Flutter engine artifacts.

android/gradle.properties

@@ -1,5 +1,7 @@
-org.gradle.jvmargs=-Xmx1536M
+org.gradle.jvmargs=-Xmx4g -XX:MaxMetaspaceSize=1g -Dfile.encoding=UTF-8
+org.gradle.workers.max=2
 android.useAndroidX=true
 android.enableJetifier=true
+# These compatibility flags are managed by Flutter's Android toolchain.
 android.builtInKotlin=false
 android.newDsl=false