Enforce writer ownership for thread archive and deletion (#35031)

## Why

Paginated threads allow only one app-server process to write at a time. Archive and delete operations must not mutate a thread or its spawned descendants while another process owns any of them.

## What changed

- Acquire paginated writer locks for the full archive or deletion set before changing rollout files, including descendants whose rollout has not materialized yet.
- Add a batch archive store operation so ownership conflicts are detected before any thread in the subtree is archived.
- Return ownership conflicts as JSON-RPC invalid-request errors and document the behavior.

## Testing

- Cover archive and deletion conflicts for owned threads and descendants, including unmaterialized rollouts.
- Verify deletion still removes rollouts with unreadable metadata.

GitOrigin-RevId: f62a3e0c1ee2631cea48dd9145b588a1486e2425

codex-rs/thread-store/src/lib.rs

@@ -24,6 +24,7 @@ pub use store::ThreadStore;
 pub use store::ThreadStoreFuture;
 pub use types::AppendThreadItemsParams;
 pub use types::ArchiveThreadParams;
+pub use types::ArchiveThreadsParams;
 pub use types::ClearableField;
 pub use types::CreateThreadParams;
 pub use types::DeleteThreadParams;