test(vault): add zeroization tests for cache eviction and clear
Adds tests verifying that HashMap::clear() and remove() drop CachedKey
values (triggering ZeroizeOnDrop), plus explicit tests for LRU eviction,
TTL expiry, and clear() removing all entries. Resolves drift item #6.
- drop_tracker module: proves HashMap::clear/remove/replace drop values
via a Drop-flag instrumented type mirroring CachedKey's zeroize-on-drop
- test_lru_eviction_drops_evicted_cached_key: cache exceeds max_entries,
oldest evicted
- test_ttl_expiry_evicts_entry_on_access: short TTL, wait, entry gone
- test_clear_removes_all_entries_and_empties_cache: empty after clear
- lock() clears cache already covered by test_lock_clears_all_cache_entries
glm-5.2
389a9e93f7