DL-581

Saiph is its own repo and product, with its own Connect package saiph.v1, its own schema and tenant GUC, and per-tenant object keys; it reads the caller from an auth.Principal built from a verified issuer token (Compass is one issuer); per-directory ACLs are in-tree .saiphacl files, and a denied read answers NOT_FOUND.

Status: Active (design, 2026-10-18)