feat: Add multi-stage Docker build and GHCR publishing workflow

[malladinagarjuna2]

Description

This PR addresses the need for an official Docker image for the MCP Conformance Server. Following discussions in the community and referencing Kuadrant/mcp-gateway issue #411, this migration moves the Docker build logic "upstream" to this repository.

The implementation follows the pattern established in the modelcontextprotocol/inspector repository to ensure consistency across the MCP ecosystem.

Key Changes

• New Dockerfile: Added a multi-stage Dockerfile at the repository root.
  • Stage 1 (Builder): Handles dependency installation (npm ci) and TypeScript compilation (npm run build) for the server located in examples/servers/typescript/.
  • Stage 2 (Release): Produces a slim, production-ready image using node:24-alpine.
• CI/CD Integration: Updated .github/workflows/ci.yml to include a publish-docker job.
  • Automatically builds and pushes images to GHCR (ghcr.io) upon official releases.
  • Supports multi-architecture builds (linux/amd64 and linux/arm64) using Docker Buildx and QEMU.
  • Includes Artifact Attestation for build provenance and security.

Testing Performed

1. Local Build: Verified the Dockerfile locally via docker build -t conformance-test . and confirmed the server starts on port 3000.

2. CI Validation: Verified the workflow on a personal fork. The publish-docker job successfully executes the build and metadata extraction steps.
   link : https://github.com/malladinagarjuna2/conformance/actions/runs/24942105590

Related Issues

• Fixes: [https://github.com/Move the conformance server Dockerfile to upstream Kuadrant/mcp-gateway#411]

[david-martin]

fyi @pcarleton (been a while, but this came up in a thread on discord as a nice thing to have https://discord.com/channels/1358869848138059966/1443175063141748828)