A structured system command. Programs and arguments are kept separate so
that callers can pass them directly to Command::new(program).args(args)
without relying on shell-style splitting, which would mishandle names
containing spaces (e.g. Windows registry keys, macOS network services).
Apply the compatibility system proxy using the platform backend and keep
all rollback state in memory. This is deliberately separate from native
eggress system-proxy inspection and from user-authored configuration.