Release v4.66.1

Changed

• MCP executionReadiness for commands, specifications, slices and the model now names every unadmitted feature with its tracking issue, in a fixed order, instead of a single required version number. (part of #309)

Fixed

• Compiler diagnostics, editor hints, the event-model board, MCP tool descriptions and the documentation no longer promise a future executable model version for generated values and responses, operations and systems, event sources and streams, or exact numbers. They now say these constructs are not admitted by any supported executable model version yet; binding still refuses them with PLAY0268. (part of #309)