feat(ci): add Docker build pipeline with version management

- Add multi-stage Dockerfile with pinned tool versions (Node 24.10.0, Go 1.25.1, Hugo 0.151.0)
- Create .env.versions as single source of truth for all tool versions
- Add GitHub Actions CI workflow for automated OCI image builds
  - Multi-arch support (amd64, arm64)
  - Automatic version loading from .env.versions
  - Docker registry push with metadata tags
- Add Taskfile tasks for local OCI image building and testing
  - task build:oci-image - Build with version-pinned dependencies
  - task test:oci-image - Build and test container locally
- Pin devbox.json to specific versions matching .env.versions
- Add comprehensive documentation (DOCKER.md, VERSIONS.md)
- Add helper script (scripts/get-versions.sh) for version extraction

This enables consistent development and production environments with
identical tool versions across local devbox, Docker builds, and CI/CD.

Taskfile.yml

@@ -86,3 +86,37 @@ tasks:
     desc: Run CI pipeline locally
     deps:
       - test
+
+  build:oci-image:
+    desc: Build OCI/Docker image with versions from .env.versions
+    cmds:
+      - |
+        set -a
+        source .env.versions
+        set +a
+        echo "Building OCI image with versions:"
+        echo "  NODE_VERSION=${NODE_VERSION}"
+        echo "  GO_VERSION=${GO_VERSION}"
+        echo "  HUGO_VERSION=${HUGO_VERSION}"
+        docker build --network=host \
+          --build-arg NODE_VERSION=${NODE_VERSION} \
+          --build-arg GO_VERSION=${GO_VERSION} \
+          --build-arg HUGO_VERSION=${HUGO_VERSION} \
+          -t ipceicis-developerframework:latest \
+          -t ipceicis-developerframework:$(git rev-parse --short HEAD) \
+          .
+
+  test:oci-image:
+    desc: Test the built OCI image
+    deps:
+      - build:oci-image
+    cmds:
+      - |
+        echo "Starting container on port 8080..."
+        docker run -d -p 8080:80 --name hugo-test ipceicis-developerframework:latest
+        sleep 2
+        echo "Testing endpoint..."
+        curl -f http://localhost:8080 > /dev/null && echo "✓ Container is running and responding" || echo "✗ Container test failed"
+        echo "Cleaning up..."
+        docker stop hugo-test
+        docker rm hugo-test