sql/builder.sh: sudo instead of su

sql/builder.sh: sudo instead of su

"su root -c" asks for the root password, which on a freshly installed debian
does not even exist: the first user administers with sudo. The two commands
were also nested (su root calling su postgres) with three levels of quoting
to get through, and the variables ended up in the string unprotected.

Now it goes straight to "sudo -u postgres" and the arguments are quoted.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014M1jiEq9cHdE5SE5j6vFuE