Effect Consistent Hash Ring

Ring placement that survives membership churn: keys and nodes hash onto the same 2^32 circle (FNV-1a with an avalanche finisher), a key belongs to the first node clockwise, and each node appears as many virtual nodes so the arcs stay statistically even. Adding a node moves roughly 1/N of the keys (all onto the new node, none between old ones) where hash(key) % N would move nearly all of them, and removing a node reassigns only the leaver's keys. The ring is an immutable sorted array swapped atomically in one Ref, so a lookup never observes a half-applied membership change, and lookup is a binary search. Solves the full reshuffle on scale-out and the lumpy ring hotspot. Pinned to effect 4.0.0-beta.98.