Changes
- Major release: redesign from 11 types + 3 interfaces to 5 types + 1 interface
- New types: Ds\Seq, Ds\Map, Ds\Set, Ds\Heap, Ds\Pair (readonly)
- New interface: Ds\Key (replaces Ds\Hashable)
- Copy-on-Write: clone and copy() are O(1), mutation during iteration is safe
- Removed: Vector, Deque, Stack, Queue, PriorityQueue, Collection, Sequence, Hashable
- Ds\Heap accepts optional callable comparator in constructor
- Ds\Pair is a readonly class with public key and value properties
- Require PHP >= 8.2