nx_stream_store.nx

nx_stream_store.nx -- LIB (M3): stream a large artifact in fixed-size chunks -> hash incrementally + append to disk, so a multi-GB .safetensors shard needs NO full-size buffer for either hashing OR storing. Composes the shipped streaming SHA-256 (nx_sha256: sha256_init/update/final) -- does not re-implement it. This is the transport half of a verified weights pull: the caller feeds fetched TCP chunks straight through ss_stream_store, then compares the returned digest to the HF lfs.oid (nx_hf_tree_parse) -- fail-closed if they differ. No TLS here -> no M32 collision with the fetch stack (transport + crypto stay in separate compilation units). license_tier: ORIGINAL