structureCacheFolder

The cache folder for the structure schematic loader.

Each loader passes its own folder and owns it exclusively: pruneStaleEntries deletes every entry its loader's file set does not account for, so two loaders sharing a folder would prune each other's entries on every load. Subfolders are safe — indexing and pruning ignore directory entries. Structures keep the root folder name that shipped before the cache machinery was shared, so entries already on servers survive the upgrade.