Replaces the misc/build.func bootstrap with the two-root core loader.
No other change: the engine contract (var_*, update_script, start,
build_container, description) is identical on both engines.
CLEAN_INSTALL now removes dotfiles (e.g. .env) along with other files, using `find -mindepth 1 -delete` instead of `rm -rf *`. Update scripts for affine, nametag, and postiz are updated to explicitly back up and restore .env (via create_backup/restore_backup or cp) BEFORE the build step that sources it, rather than relying on the wipe preserving dotfiles.
