Add Android CI workflow

[hoopsi73]

Summary

• add an Android GitHub Actions workflow that checks out the project, configures JDK 17, caches Gradle, and runs assembleDebug, test, and lint
• expand the repository gitignore so Android Gradle and build outputs are excluded from version control

Testing

• ./gradlew assembleDebug (fails: Android SDK path is not configured in this environment)

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https://chatgpt.com/codex/tasks/task_e_6900cfff13688332bb9f08832fcb9d51

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Configure Android SDK before running Gradle tasks

The workflow runs ./gradlew assembleDebug, test, and lint without ever installing or pointing to an Android SDK (no ANDROID_SDK_ROOT/ANDROID_HOME export and no local.properties is generated). GitHub-hosted Ubuntu runners do not have the SDK path configured by default, so these Gradle steps will consistently fail with “SDK location not found” rather than providing useful CI feedback. Add a setup step (for example, android-actions/setup-android or explicitly setting ANDROID_SDK_ROOT and writing local.properties) before invoking Gradle.

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