TCM_REACT_GONE
What an import of #tcm/react is told: it was the module tcm generated for React's routes, links and data, which
are the react library tcm ships now.
export const TCM_REACT_GONE = '#tcm/react is the react library now: `tcm lib add tcm react` mounts the one tcm ships (at <root>.lib.react), and code imports it from there: `import { useData } from "#codebase/<root>/lib/react"`'