Indeed, in DW would the GM be allowed to narrate a screaming cook on a successful pick lock check? It seem like something that would require a (hard) move?
Not as a result of that move, no. This is among the rules that bind the GM--GMs are not free to just do whatever they want, whenever they want, no matter what. They are bound to respect the outcome of moves for the same reason that GMs are bound to respect the outcome of rolls in D&D.
The thing you're describing would be like a player unequivocally succeeding on a Perception check, e.g. getting a nat 20, and then the GM unilaterally deciding "nope, you actually failed because I decided that's what should happen". I'm pretty sure multiple people in this thread have already said that that would be unacceptable.
If not, would that mean the GM cannot plan out in advance that there should be a cook sitting eying the door impatiently, waiting for fresh bread for breakfast to arrive?
Not
as a result of that move, no. And such a literally completely unpredictable, unforeseeable "gotcha" moment would be, I should think, considered really inappropriate GMing even for those who favor a "traditional GM" approach. Such an action would mean that the GM had set up the player for absolute unavoidable failure without any ability to know, predict, or react.
If a GM did this to me in a D&D game, we would have words. Possibly immediately, if the screaming cook immediately results in hugely bad problems.
But, if I may, let me give you an example from my own game, which shows how something
almost like what you're describing--what I think you really
want to describe, but did not here--very much can occur in DW.
In my game,
Jewel of the Desert, my players had gone to some pretty extensive lengths to make sure they did in fact capture a criminal. He was a dragonborn, but also someone who had joined up with the Uyun al-Thuban, the "Serpent's Eye" gang--which is a front established by a black dragon trying to take over the city in secret. The ganger's name was Khabir al-Sadiqqi. Despite being captured, Khabir was supremely confident in interrogation. The group could tell that he wasn't gonna crack without actually torturing him, which the party wasn't interested in doing, so they decided to exploit his confidence--he clearly expected to be
broken out by the gang, so they
allowed him to get broken out, arranging for that breakout to be relatively painless breakout. Their target: use this little fish to lead them to a big fish--a gang "overboss" type!
Unfortunately, what they didn't know is that someone they relied on as part of their planning, a non-noble genie alchemist named Musa, may truly be
actually a legitimate businessman...but one who is under the black dragon's control, albeit at several layers removed. As a result, although their plan went off well and they succeeded in many ways, their ultimate goal--capturing the "overboss"--was denied to them from the very beginning, because they had trusted Musa. Musa didn't actually rat them out, not intentionally anyway, but the black dragon watches Musa's activity and saw what they were doing. Not wanting its secrets to be revealed, but also wanting to keep the party in the dark as long as possible, the black dragon pulled out as many resources from the target warehouse as it could, sent away all but a barebones and ill-informed crew to keep up appearances, and had the "overboss" appearing via a powerful illusion, rather than being physically present.
As the party investigated, they found the place unusually low on guards (first sign that things weren't as they seemed), and then when they dug into one of the rooms, they found a lot of the boxes were full of just sawdust, or genuinely empty, the second bad sign. They didn't quite put two and two together until they reached the final room, where Khabir and the "overboss" (or, rather, his illusionary form) were waiting. The overboss had a relatively pleasant but disdainful conversation with them, and then revealed (even to Khabir!) that he wasn't actually there physically, and thus he would be taking his leave--leaving Khabir to his fate, punished for being so foolish as to bring the law down on this location and disrupting the gang's plans so badly.
It was still, overall, a victory. The party got a lot of good information, they still disrupted the gang, and the gang wasn't as thorough with their clean-up as they could've been, leaving enough traces of evidence behind to point to new things. But the
overall goal was a failure before the mission even began, not because I had any plan whatsoever to make this happen, but because they relied on someone they shouldn't have.
The key difference, here, is that even though they didn't know not to trust Musa in this, they
could have known. There have been plenty of hints that he isn't quite as squeaky-clean as he seems, and he has already deceived the party about where his loyalties lie once before. (Well, not so much "deceived" as "consciously avoided disclosure"--mere omission, and the party was terribly obliging by never asking a direct question!) There were ways for them to discover the magic being used, too, but they did not use those methods (in part because they feared doing so might alert the gang to their intentions, which was a slim but non-negligible possibility.) In comparison to your cook-watching-the-door, they
very much could have prevented this from ever happening, or at least learned that it had happened before the final reveal--whereas your cook-watching-the-door as presented cannot be prevented, cannot be known in advance, and will always lead to a pretty substantial failure
completely independently of the players' actions. That doesn't sit well with me.
As I said: my players were dealt a meaningful defeat here, and it happened totally outside the context of rolling or not rolling. They actually did very well on their plan's execution! They just trusted the wrong person, and that had ripple effects--not total 100% loss, but losing the grand prize and weakening the consolation prizes. The defeat was actually something arising from them making a bad move, not from the GM inserting a guaranteed-fail condition.