Structural/aggregate ops in lib/erlang/lists-ext.sx: flatten/1 deep
flatten, max/1 and min/1 by full Erlang term order (badarg on empty).
Extreme-finder uses er-ext-lt?'s SX boolean directly in if (er-truthy?
only recognises Erlang bool atoms). lists_ext suite 52 -> 62.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>