Consolidate CLI verbs; retire overlapping commands

The verb surface accumulated overlapping cleanup commands. Consolidate
so each cleanup verb has one meaning:

- Rename 'database purge' -> 'database delete'. The command removes the
  SQLite file entirely; "purge" wrongly suggested purging contents.
- Fold 'snapshot cleanup' into 'prune'. Prune now runs three passes:
  reconcile local snapshots against the remote (previously the
  standalone cleanup command), drop orphaned local rows, then delete
  unreferenced remote blobs. One command, one mental model.
- Delete 'store info'. Its output was a strict subset of 'remote info',
  which already prints storage type + location. Any user reaching for
  either should reach for 'remote info'.
- Drop 'snapshot remove --all'. It duplicated 'remote nuke --force'.
  'remote nuke' is the single supported entry point for wiping the
  destination store.

Also update the storage-binding error message to reference the new
'vaultik database delete' name.

internal/vaultik/prune.go

@@ -58,6 +58,14 @@ func (v *Vaultik) Prune(opts *PruneOptions) error {
 	if err := v.EnsureStorageBinding(); err != nil {
 		return err
 	}
+	// First reconcile local snapshot records against remote metadata:
+	// any local snapshot whose manifest is missing from the destination
+	// store is treated as gone. This used to be the separate 'snapshot
+	// cleanup' command and is now folded in so a single 'vaultik prune'
+	// gets the local index fully back in sync with the destination.
+	if err := v.CleanupLocalSnapshots(); err != nil {
+		return fmt.Errorf("reconciling local snapshots with remote: %w", err)
+	}
 	if _, err := v.PruneDatabase(); err != nil {
 		return fmt.Errorf("pruning local database: %w", err)
 	}