Android build failure due to deprecated package attribute and outdated AGP configuration

[Madhan-Rkv-10]

Description

When building the Dual Screen example project with the latest Android Gradle Plugin (AGP 8+), the build fails due to:

1. The use of the deprecated package attribute in AndroidManifest.xml
2. An outdated AGP configuration in build.gradle

AGP 8+ requires that the package name be defined in Gradle using the namespace property for source code and applicationId for the APK. Keeping the package in the manifest causes a build error.

Steps to Reproduce

1. Clone the repository
2. Upgrade Flutter to the latest stable
3. Open android folder in Android Studio
4. Build the project using AGP 8+
5. Observe build failure with error regarding package attribute