The product README was under windows/ after the move, but it was never a component readme: it is the download page, the feature guide and the contribution guide for the whole product, so it goes back to the root and windows/ gets a real component readme.
AGENTS.md at the root now carries the repository map, the component boundaries that used to be cross-repository rules, and the release process, since the scripts that process drives live at the root. The component files keep what is genuinely theirs and say which paths they are relative to. References that named sibling repositories now name sibling directories, and the lock documentation records that Server, the pages, the GUI framework and the installer are no longer inputs to pin.
Preparation for folding Server, UI, UiHtml, Installer, ImeLog and TsfEditControl into this repository. The Windows tip's own sources, build files and local build scripts move under windows/ so every component sits at the same level. Product-level files stay at the root: the lock, the release manifest, the shared CI scripts, the integration tests, the docs and the Engine submodule.