- CRITICAL: confirm_delete was never reset when pressing other keys
after 'd'. User could navigate, re-mark, press 'd' again and
snapshots would be deleted without confirmation
- expand_all: only expanded currently visible datasets, not nested
collapsed ones. Now recursively collects from root_entries
- is_last for snapshots: showed wrong tree connector when parent
had both child datasets and snapshots (snapshots are always last)
- auto-refresh message hardcoded "30s" instead of config value