Sounds weird when you ask the question that way, but if you ask "is there a non-black marble in the bag?" the answer is clearly no. So the question is more like: Should "all marbles in the bag are black" be exactly equal to "not(is there a non-black marble in the bag)".
I was checking out the docs for that and a few other similar solutions too. This is very true. Most of the secret managers are primarily intended for config-like data.
No, that's fine. I'd shy away from third party libs though, would probably use what Node.js provides out of the box. Or possibly something in the database, but I've never looked into that. Just don't roll your own crypto _library_, obviously.
Other way around. Of course physics has nothing to do with whether a theorem is true or false - but it has everything to do with whether our universe satisfies that theorem's hypotheses.
I'm also struggling to make sense of what you're saying. Non-local measurement outcomes have very little to do with causality. Are you arguing against specific interpretations such as Bohmian mechanics, which require privileged space–time foliations?