Public repositories share demos right after a restart

A public repository without its own demo site shares its demos on the owner's personal site, and Obeya asks the forge whether the repository is public. Until now, right after every restart, such a repository counted as private until the forge answered, so agents resumed in that window didn't write the page that goes with their demo. Obeya now remembers the forge's last answer across restarts, and resumed agents write their demo's page as usual.