Server initialize response update to last spec (add title, description)

[yannj-fr]

To match the last protocol spec, the Implementation schema must be updated and new attribute propagated on server constructor.

Motivation and Context

To match the last protocol specification update.

How Has This Been Tested?

End To End test, also added to the test suite

Breaking Changes

n/a

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

Also fix the version attribute which was not flowing to the _mcp_server object so was always defaulted to package version.

[maxisbey]

Related: #1793, #1799