CVE-2026-44449: Lumiverse: SMB `exists()` basename injection via smbclient `!cmd` escape

Lumiverse is a full-featured AI chat application. Prior to 0.9.7, when the primary toSmbPath(fullPath) call throws, the method falls back to a dirname/basename split and only validates the directory prefix. The basename is concatenated directly into the smbclient -c script without validation. smbclient interprets ; as a subcommand separator and !cmd as a local-shell escape that runs cmd on the host. A path whose directory component is clean but whose basename contains "; !<cmd>; echo " achieves arbitrary command execution on the Lumiverse server. This vulnerability is fixed in 0.9.7.