add: pluggedin-mcp-proxy to Aggregators section

[ckaraca]

Description

This PR adds the pluggedin-mcp-proxy to the Aggregators section. Plugged.in MCP Server acts as a proxy server that combines multiple MCP servers into a single unified interface with extensive visibility features. It fetches tool, prompt, and resource configurations from the plugged.in App and intelligently routes requests to the appropriate underlying MCP servers.

Features

• Universal MCP Compatibility with any MCP client (Claude, Cline, Cursor, etc.)
• Multi-Server Support for both STDIO and WebSocket MCP servers
• Namespace Isolation to keep joined MCPs separate and organized
• Multi-Workspace Layer to switch between different sets of MCP configurations
• Extensive visibility of prompts, resources, and templates across all connected servers
• Discovery functionality to see details of available servers and tools
• Playground for extensive debugging when building MCP Servers
• Collections creation for different clients (Claude Desktop, Cursor, Cline)
• Tool Management across all connected MCP servers
• Intelligent Routing of tool calls to the appropriate underlying MCP server

Checklist

• The entry follows the repository's format
• The description is concise and informative
• The appropriate emojis are used (TypeScript, Local Service)
• The GitHub repository link is valid