Read a saved knowledge document version

Reads retained saved snapshots of a non-archived knowledge document. Partner tokens require knowledge-docs; API keys or delegate tokens use knowledge read access. Delegate callers must remain active company members and currently be able to view the document; membership, document and team authorization use primary reads. API keys and partner tokens are company-scoped. Archived, deleted, or inaccessible documents return 404. There is no archived override. Snapshots older than the current document creation time are excluded so a reused document ID cannot expose a deleted document history. These are saved versions, not unsaved drafts or a complete edit audit: rapid saves may merge and older history may be pruned (normally 50 versions retained). savedBy records the saver, not necessarily the author of every passage; Hiro before/after snapshots both name the approver. No restore or mutation is performed. Returns historical metadata and read-only top-level text blocks, up to 20 blocks and 20,000 text characters per page. Each block is capped at 10,000 characters with explicit truncation; specialized blocks may omit non-text/formatting details. offset/nextOffset count blocks. No editable flags or current editing-version token are returned. Unsupported legacy snapshots return 400. The top-level name is the current title; snapshot.name is the historical title. Any document link opens the current document.