fix: update openapi.yml to include statusChangedAt

[jeffmaury]

Fixes #1169

Update the openapi.yml to add a missing field

Motivation and Context

openapi.yml was not in sync with live data

How Has This Been Tested?

Validated the openapi.yml file

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 Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[rdimitrov]

Thanks for helping with this, @jeffmaury! 🙏