Restore parameter text and explain rejected renames

When Studio rejects a parameter rename, the Parameters field can continue displaying the proposed name even though the declaration and saved project retain the original name. No rename preview appears and the project is not marked as modified, making a correct compiler diagnostic appear inconsistent with the editor.

Rejected parameter renames should restore the displayed declaration and show a clear explanation beside the Parameters field. Preserve existing source, unsaved work, and undo history.