pub fn checksum(data: &[u8]) -> [u8; 8]Expand description
Compute the xxHash3-64 checksum of data, big-endian (xxhash canonical
byte order — the value embedded in every StorageEnvelope).
Non-cryptographic: detects corruption, not tampering. For tamper-resistance
use AES-256-GCM (the auth tag), not this checksum. Intentionally unbounded —
a single-pass, allocation-free O(n) hash over caller-materialized bytes; the
MAX_UNCOMPRESSED_SIZE cap is StorageEnvelope’s decompression-bomb concern.