Eric Coissac
dfce956162
Add an `Iter` struct that implements `Iterator` and `ExactSizeIterator` to enable idiomatic traversal of `&PersistentCompactIntVec`. The iterator maintains `slot` and `overflow_pos` state to correctly yield `u32` values from both primary and overflow memory regions. Includes three unit tests validating iteration correctness against direct indexing, accurate `len()` tracking, and proper reference-based iteration.
toto