📦 Add Docker containerization support

[floriscornel]

Description

Create and publish a Docker image for the Teams MCP server to provide an alternative deployment method alongside npm installation.

Goals

• Create a Dockerfile with optimized build stages
• Set up automated Docker image builds in GitHub Actions
• Publish to Docker Hub and/or GitHub Container Registry
• Update documentation with Docker usage instructions
• Include health checks and proper signal handling

Benefits

• Easier deployment and distribution
• Consistent runtime environments
• Simplified installation for users who prefer containers
• Better isolation and security

Acceptance Criteria

• Docker image builds successfully and runs the MCP server
• Image is published to public registry with proper versioning
• Documentation includes Docker installation and usage examples
• Image size is optimized (multi-stage builds, minimal base image)