Add Docker image versioning for release tags

[Copilot]

This PR implements automatic Docker image building and versioning when release tags are created, addressing the need for versioned Docker images that correspond to project releases.

Changes Made

Docker Workflows Enhanced

Updated all three Docker workflows (docker-api.yml, docker-admin.yml, docker-customer.yml) to:

• Add release: types: [published] triggers alongside existing master branch triggers
• Implement conditional logic to handle both development and release builds
• Build and tag images with version numbers extracted from release tags

Versioning Strategy

When a release is published (e.g., v1.2.3), the workflows now:

• Build Docker images tagged with the specific version: tolfixorg/cpg-api:v1.2.3
• Also tag the same image as latest: tolfixorg/cpg-api:latest
• Push both tags to DockerHub

Backwards Compatibility

Development workflow remains unchanged:

• Master branch pushes continue to build images with build-{run_number} tags
• No disruption to existing development processes

Documentation Updates

Updated the API README to:

• Correct the Docker image name from tolfixorg/cpg:latest to tolfixorg/cpg-api:latest
• Document the availability of versioned tags

Example Usage

After this change, users can pull specific versions:

# Pull a specific release version
docker pull tolfixorg/cpg-api:v1.2.1
docker pull tolfixorg/cpg-admin:v1.2.1
docker pull tolfixorg/cpg-customer:v1.2.1

# Pull the latest stable release
docker pull tolfixorg/cpg-api:latest

Technical Implementation

• Uses GitHub's GITHUB_REF environment variable to extract tag names
• Optimized Docker builds with multiple tags to avoid rebuilding the same image
• All YAML syntax validated for correctness

This enhancement enables users to deploy specific versions of CPG applications using Docker, improving deployment stability and version management.

Fixes #60.

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