feat: implement CI/CD pipeline

[mustalk]

This pull request introduces a Continuous Integration (CI) and Continuous Deployment (CD) pipeline using GitHub Actions. The goal is to automate key development workflows, including static analysis, testing (unit and UI), APK building, and the creation of versioned GitHub Releases with debug APKs for internal testing and demonstration purposes.

A key aspect of this implementation is the modularization of the deployment logic into a reusable composite GitHub Action, enhancing maintainability and clarity of the main workflow file.

Key Changes & Highlights:

1. Unified CI/CD Workflow (android-ci-cd.yml):
This single workflow orchestrates both CI and CD processes.

Continuous Integration (CI) Stages:

• Triggers: On pushes to main and branches matching 'feat/', 'chore/', 'bugfix/', 'test/', 'refactor/', 'hotfix/'.
• Concurrency Control: Automatically cancels previous workflow runs for the same branch or pull request to save resources and ensure focus on the latest changes.
• Setup:
  • Performs code checkout.
  • Sets up JDK and Gradle, leveraging caching for Gradle dependencies and build outputs to speed up builds.
• Quality Gates:
  • Static Analysis: Runs Detekt and KtLint in parallel to enforce code style and detect potential issues early.
  • Unit Tests: Executes ./gradlew test to validate core application logic.
• Build & UI Testing:
  • Build Debug APK: Generates a debuggable Android application package.
  • Android Emulator Setup: Configures an Android emulator with AVD caching for faster UI test execution.
  • UI/Instrumented Tests: Executes ./gradlew connectedCheck to run UI tests on the configured emulator.
• Artifacts:
  • Uploads test reports (from both unit and UI tests) for review.
  • Uploads the generated debug APK as a build artifact for consumption by the CD stage.

2. Modular Continuous Deployment (CD) via Reusable GitHub Action:
The deployment logic is encapsulated into a dedicated reusable composite action to promote modularity and simplify the main workflow.

Reusable Action: .github/actions/execute/android-deploy/action.yml

• Encapsulated Logic: This action is responsible for the entire deployment process:

  • Extracting versionName and versionCode from app/build.gradle.kts.
  • Downloading the debug APK artifact (name dynamically passed from CI).
  • Creating or updating a Git tag (e.g., v1.2.3). If the tag exists, it's deleted and recreated to point to the current commit, ensuring the tag always reflects the latest release content.
  • Generating comprehensive release notes including version, build number, commit SHA, a link to the last merged PR to main (if available), and instructions for downloading the debug APK.
  • Creating a new GitHub Release if one doesn't exist for the tag, or updating an existing one. Releases are published directly (not drafts).
  • Uploading the debug APK to the GitHub Release assets, replacing any existing APK with the same filename to ensure the latest build is always available.

• Usage in Main Workflow: The android-deploy job within android-ci-cd.yml has a single step that uses: ./.github/actions/execute/android-deploy with necessary inputs like the GitHub token, CI artifact name, and desired release APK filename (e.g., mustalk-mars-rover-debug.apk).

3. Key Optimizations & Workflow Features:

• Optimized Cache Strategy: Implements a read-only cache for feature branches and a read-write cache for the main branch to balance build speed and cache freshness.
• Emulator Resource Management: Optimized emulator configuration (memory, disk, heap) and includes resource monitoring with optional disk cleanup for CI runner space management.
• Automated Versioning & Release Management: Fully automates Git tagging and the creation/update of GitHub Releases.

Important Note on Deployment:

• The debug APKs distributed through this CD pipeline are intended strictly for internal testing, QA, and demonstration.
• For production releases, a separate, more robust strategy would be required, involving code signing, potentially different build flavors, and distribution through official app stores.