- Add McpServerStatusCommand with ListInputHandler: Command Palette
  entry shows running/stopped state and lets user start or stop servers
- Extract _start_servers/_stop_servers helpers
- Add MCP Commander.sublime-commands for palette registration
- Rewrite README and install.txt for pure-Python SSE architecture
- Add messages/1.3.0.txt upgrade note
- Update module docstring; bump version to 1.3.1

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>