id generators - from `Date.now()` to snowflake

aight so today we're talking about id generators. seems boring on paper, but stay with me — this is one of those topics where every line of complexity comes from a real production problem someone hit at scale. and the cool part is the entire problem statement collapses to: write a function that spits out something unique every time it is invoked . that's it. no service, no microservice, no fancy…