Implements the new optional message field for progress notifications as
defined in the MCP specification update. This allows servers to provide
descriptive status updates alongside progress values.
Changes:
- Add optional message field to ProgressSchema in types.ts
- Add tests for progress notifications with message field
- Update protocol tests to verify message field handling
Refs: https://github.com/modelcontextprotocol/modelcontextprotocol/pull/197🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>