Set up GitHub Actions CI pipeline for automated testing and Docker builds

[Copilot]

This PR implements a comprehensive GitHub Actions CI pipeline to automate testing and Docker builds as requested in issue #27.

What's Added

CI Workflow (.github/workflows/ci.yml)

The new workflow provides two main jobs:

Test Job - Runs on every push to main and all pull requests:

• Sets up Java 21 with Eclipse Temurin distribution
• Implements Gradle dependency caching for faster subsequent builds
• Automatically handles gradlew permissions
• Runs the full test suite with ./gradlew test
• Builds the application with ./gradlew build

Docker Job - Runs only on pushes to main branch after tests pass:

• Uses Docker Buildx for advanced build capabilities
• Authenticates with GitHub Container Registry (ghcr.io) using built-in GITHUB_TOKEN
• Builds and pushes Docker images with intelligent tagging:
  • latest for main branch
  • Branch-specific tags (main-<sha>)
  • SHA-based tags for precise version tracking
• Implements Docker layer caching to optimize build performance

Key Benefits

• Automated Quality Assurance: Every code change is automatically tested before merge
• Continuous Deployment: Docker images are automatically built and published on main branch updates
• Performance Optimized: Gradle and Docker caching significantly reduce build times
• Zero Configuration: Uses GitHub's built-in authentication and registry
• Multi-Environment Support: Separate workflows for testing (PRs) and deployment (main)

Technical Details

The workflow leverages modern GitHub Actions features including:

• Dependency caching with actions/cache@v4
• Docker multi-platform builds with docker/setup-buildx-action@v3
• Automated container registry authentication
• Conditional job execution (Docker builds only on main)

The implementation follows CI/CD best practices and provides immediate feedback on code quality while automating the deployment pipeline for the Spring Boot application.

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[Copilot]

Pull Request Overview

Sets up a GitHub Actions CI pipeline to run Gradle tests/builds and build/push Docker images to GHCR, and slightly simplifies the Dockerfile.

• Adds CI workflow with separate test and Docker build jobs
• Implements Gradle and Docker layer caching
• Removes permissive .gradle directory creation from Dockerfile

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 4 comments.

File	Description
.github/workflows/ci.yml	Adds CI pipeline with test and Docker build/push jobs, caching, and metadata-driven tagging
Dockerfile	Removes unnecessary .gradle directory creation and chmod

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[Copilot]

The workflow uses GITHUB_TOKEN to push to GHCR but does not explicitly grant packages: write permission. Without explicit permissions, pushes can fail or run with overly permissive defaults; add least-privilege permissions to the docker job: permissions: contents: read, packages: write.

Suggested change

	runs-on: ubuntu-latest
	runs-on: ubuntu-latest
	permissions:
	contents: read
	packages: write

[Copilot]

Gradle's build task executes tests by default, so running test and then build runs tests twice. Either run only ./gradlew build, or keep the test step and change the build step to ./gradlew build -x test (or use check + assemble) to avoid redundant work.

Suggested change

	- name: Run tests
	run: ./gradlew test

[Copilot]

Gradle's build task executes tests by default, so running test and then build runs tests twice. Either run only ./gradlew build, or keep the test step and change the build step to ./gradlew build -x test (or use check + assemble) to avoid redundant work.

Suggested change

	run: ./gradlew build
	run: ./gradlew build -x test

[Copilot]

[nitpick] Actions are referenced by mutable tags (e.g., @v4/@v3/@v5); pin them to specific commit SHAs to prevent supply-chain attacks and ensure reproducibility. Apply this to all uses steps in this file (lines 14, 17, 23, 47, 50, 53, 61, 70) by replacing the tag with the corresponding commit SHA from each action's repository.