docs: enhance README with Claude Desktop STDIO integration

[jcoffi]

📚 Documentation Enhancement: Claude Desktop Integration

This PR significantly improves the documentation to better highlight the existing STDIO support for Claude Desktop and other MCP clients.

🎯 Key Improvements

Claude Desktop Integration

• ✅ Added dedicated "Claude Desktop Integration (Recommended)" section
• ✅ Step-by-step setup instructions with config file examples
• ✅ Highlighted npx installation method for easy setup
• ✅ Enhanced server modes documentation for both STDIO and HTTP

Enhanced Testing

• ✅ Added comprehensive STDIO test suite (test-stdio.js)
• ✅ New npm run test:stdio command for easy validation
• ✅ Tests verify MCP protocol initialization, tools listing, and JSON-RPC communication

Better Documentation Structure

• ✅ Enhanced README with Claude Desktop setup instructions
• ✅ Mode-specific prerequisites and setup instructions
• ✅ Clear usage examples for both development and production

🚀 What Users Get

Simple Claude Desktop Setup:

{
  "mcpServers": {
    "quiver": {
      "command": "npx",
      "args": ["-y", "github:usnavy13/quiverMCP"],
      "env": {
        "QUIVER_API_TOKEN": "your_token_here"
      }
    }
  }
}

Easy Testing:

npm run test:stdio  # Validates all 21 QuiverAPI tools

📋 Files Changed

• README.md - Comprehensive documentation updates
• CHANGELOG.md - Documented improvements
• package.json - Added STDIO test script
• test-stdio.js - New STDIO test suite

✅ Testing

• All existing functionality preserved
• STDIO test suite passes (validates 21 tools)
• No breaking changes to existing code

This enhancement makes it much clearer that QuiverMCP already supports STDIO and provides excellent Claude Desktop integration out of the box!