feat: add secure container deployment, GHCR release workflow, and dual MCP transport

[Gauweiler42]

Summary

• add a secure multi-stage Docker image for the MCP server with non-root runtime, production-only dependencies, and a .dockerignore
• add GitHub Actions release workflow to build and publish container images to GHCR on release.published (plus manual dispatch)
• add env-based config support while preserving inline CLI args precedence for existing Claude Desktop setups
• implement dual MCP transport support: default stdio mode plus http mode (Streamable HTTP with POST/GET/DELETE session handling)
• document container runtime/build variables and remote MCP usage in the README

Why

This enables production-grade container deployment and release publishing while keeping backward compatibility for stdio clients and adding remote MCP support for HTTP-based clients.

Validation

• npm run build
• npm test -- tests/config.test.ts (12 passing)
• local Docker build succeeded
• HTTP mode smoke test confirmed /mcp endpoint reachable and bot connection to Minecraft server