Add QuantConnect MCP Server to README

[DerekMelchin]

Description

Add QuantConnect MCP Server

Motivation and Context

Adds a new server to the list in the README

How Has This Been Tested?

Yes, we've tested with several clients as shown here. We also have a suite of unit tests.

Breaking Changes

No

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

[jaredbroad]

This is the only official QuantConnect MCP.