Default Ankusa.BlobStore: immutable objects on the local filesystem.

Objects live under opts[:root] (an absolute path), by default Config.path(config, "segments"). A dedicated claim store (claim_check.blob_stores: [{LocalFS, root: "/shared/claims"}]) points it elsewhere — at a directory every node and the gateway mount, say.

Writes are atomic (temp file + rename) and durable (file and directory fsyncs), so a reader never sees a half-written object and a committed one survives power loss. Reads use :file.pread/3 for a single-record range GET without slurping the whole object into memory.