docs(mcp): update GitHub MCP server guide to use official server

[dealako]

Overview

The GitHub MCP setup guide in mcp/github.md references the deprecated @modelcontextprotocol/server-github npm package, which was deprecated as of April 2025. This issue tracks updating the guide to use the official GitHub MCP server.

Problem

• The npm package @modelcontextprotocol/server-github is deprecated as of April 2025.
• The guide does not reflect the current recommended setup options provided by GitHub.

Proposed Changes

• Replace deprecated npm-based configuration with the official ghcr.io/github/github-mcp-server image.
• Add three Claude Code setup options:
  • Option 1 (Recommended): Remote HTTP endpoint (https://api.githubcopilot.com/mcp) for Claude Code 2.1.1+
  • Option 2: Local Docker deployment
  • Option 3: Binary installation (no Docker)
• Update Cursor AI configuration to use the Docker image.
• Add a Troubleshooting section.
• Update .markdownlint.json to exempt code blocks and tables from the MD013 line-length rule.

References

• GitHub MCP Server — Official Installation Guide for Claude
• GitHub MCP Server Repository
• PR: docs(mcp): update GitHub MCP server guide to use official server #40