Content-uuid

JCS → SHA-256 → uuidv8 (src/integrity/content-uuid.ts).

FNV toUuid stays for cheap folds; SHA seals proofs.

Verify on read — mismatch is tamper.

Receipt: b14d6e94-a846-82b8-90b1-669922beaac5 · set 0eed975c-2b44-87d3-b56b-3fea8ab14f83