Return the authoritative system execution environment and registered logical program names. Program availability is already reflected in system_exec; do not probe with which, where, command -v, or Get-Command.

Execute one registered system program directly through a cross-platform program-and-arguments interface. Use only program names in the enum. Pass arguments separately without shell quoting. Shell operators, pipelines, redirects, command substitution, and environment expansion are not supported. Do not probe or guess alternative executable names.