The production backend Dockerfile was looking for Gradle files in a
backend/ subdirectory that doesn't exist in the repo structure:
- gradlew lives at repo root, not backend/gradlew
- gradle/ wrapper dir lives at repo root, not backend/gradle/
- settings.gradle lives at repo root, not backend/settings.gradle
Fixed by copying root-level Gradle files and placing backend-specific
files in the backend/ subdirectory. Also added :backend: subproject
prefix to Gradle tasks and corrected the output JAR path.
This fixes the deploy pipeline failure:
failed to calculate checksum: /backend/settings.gradle: not found