Implement n8n-MCP integration

This commit adds a complete integration between n8n workflow automation and the Model Context Protocol (MCP):

Features:
- MCP server that exposes n8n workflows as tools, resources, and prompts
- Custom n8n node for connecting to MCP servers from workflows
- Bidirectional bridge for data format conversion
- Token-based authentication and credential management
- Comprehensive error handling and logging
- Full test coverage for core components

Infrastructure:
- TypeScript/Node.js project setup with proper build configuration
- Docker support with multi-stage builds
- Development and production docker-compose configurations
- Installation script for n8n custom node deployment

Documentation:
- Detailed README with usage examples and API reference
- Environment configuration templates
- Troubleshooting guide

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.env.example

@@ -0,0 +1,13 @@
+# MCP Server Configuration
+MCP_SERVER_PORT=3000
+MCP_SERVER_HOST=localhost
+
+# n8n Configuration
+N8N_API_URL=http://localhost:5678
+N8N_API_KEY=your-n8n-api-key
+
+# Authentication
+MCP_AUTH_TOKEN=your-secure-token
+
+# Logging
+LOG_LEVEL=info