CI: replace Ant build step with Gradle assemble for Android project

[Copilot]

The build Actions job failed because the workflow invoked Ant (build.xml), but this repository is a Gradle-based Android app. This update aligns the workflow with the actual build system so the CI build job executes the project’s real build path.

• Workflow alignment

  • Replaced the Ant invocation with Gradle wrapper execution in .github/workflows/ant.yml.
  • Updated the build step to run assembleDebug, matching the project’s Android artifact build path.

• Java runtime compatibility

  • Updated workflow JDK setup from 11 to 17 to match current Android Gradle plugin/toolchain requirements.

• Resulting CI command path

  - name: Set up JDK 17
    uses: actions/setup-java@v4
    with:
      java-version: '17'
      distribution: 'temurin'
  
  - name: Build with Gradle
    run: |
      chmod +x ./gradlew
      ./gradlew --no-daemon assembleDebug