Add the implemented Agent Note owning the win32 rung decision: mxc rejected (OS floor 24H2, BaseContainer tier only on 25H2+ with the OS feature enabled, and arbitrary-path reads demand wholesale host DACL writes), AppContainer rejected (no ambient read access — arbitrary-path reads unsupported), landstrip already rejected and AppContainer-shaped. Link the note from the backend README pair and restate the choice in the PR description.