feat: add Data4Library MCP server to the readme

[isnow890]

Description

Add Data4library MCP server for Korea's Library Information Naru API integration

Server Details

• Server: data4library-mcp
• Changes to: Adding new MCP server to the registry

Motivation and Context

This MCP server provides comprehensive access to Korea's national library system through the Library Information Naru API. It enables AI assistants to help users find libraries, search books, check availability, analyze reading trends, and discover nearby libraries using GPS location. This fills a gap for Korean library services in the MCP ecosystem.

How Has This Been Tested?

• Tested with Claude Desktop and other MCP-compatible clients
• Verified all 25 API endpoints work correctly
• Tested GPS-based nearby library search functionality
• Validated book search, availability checks, and statistics retrieval
• Confirmed proper error handling for missing API keys and invalid requests

Breaking Changes

None - this is a new server addition

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

• Built using FastMCP framework with Zod schema validation
• Supports both authenticated (with API key) and limited functionality modes
• Implements custom GPS-based library discovery not available in the original API
• Provides smart tool chaining for complex queries (e.g., finding region codes before library search)
• Includes comprehensive session statistics and debugging features
• All 25 tools are thoroughly documented with Korean usage scenarios