## Why
`Attach` delivers live events only. Clients also need access to stored turn metadata and item content.
## What changed
- Add `Client::list_turns` and `Client::list_items` using native gRPC history endpoints, with optional turn filtering for items.
- Expose page limits, sort order, access mode, and forward/backward cursors. Each call returns one page in server order without automatic pagination or retries.
- Preserve raw response and row payloads alongside typed summaries and item timestamps. Retain unknown item variants and command sources without typed summaries.
- Document cursor reuse and history/live overlap: history pages do not provide an atomic boundary with `Attach`, and coordinated reconciliation still requires caller-managed state.
## Testing
Add wire-fixture tests for request encoding, explicit pagination, raw payload preservation, unknown data, malformed rows, empty pages, RPC errors without retries, and diagnostic redaction.
GitOrigin-RevId: f507530b8e431236bc7e19d867517af56f74644f
Benjamin Carlsson
bc4116e4cd