#382
zbx temporary installs persist in zb list
running zbx for a formula that is not already installed says it is installing temporarily, but it uses the normal installer path and leaves the formula plus dependencies recorded in zerobrew state. repro: run zbx ffmpeg, then run zb list. expected: zbx either cleans up temporary installs after execution or uses an isolated temporary install path that does not mutate the normal installed package list. actual: ffmpeg and its dependency graph remain visible in zb list after the command exits. we should either make zbx truly temporary or change the wording/docs if persistence is intentional.