run_pbwo4 and run_sampling previously hardcoded 1 GeV mono-energetic
e- primaries. Both now accept a trailing energy_GeV CLI argument
(default 1.0, unchanged) so datasets at other energies can be
produced without recompiling.
Concurrent job launches can land in the same wall-clock second, causing
G4System::init's time-based seed (seed=-1) to collide and produce
byte-identical physics across separately-named shards. Falls back to
the existing time-based seed if the variable is unset, empty, or invalid.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>